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TRANSCRIPT
groovys Documentation100
zj
2016 01 14
Contents
1 311 Groovy 312 Groovy 5
2 Indices and tables 25
i
ii
groovys Documentation 100
Contents
Contents 1
groovys Documentation 100
2 Contents
CHAPTER 1
11 Groovy
111
Groovy windows Mac OSX Linux Cygwin GVM Groovy Groovy
bull zipBinary Release | Source Release
bull JavaDoc and zipped online documentation
bull amp amp Distribution bundle
invokedynamic
Groovy (snapshot) CI Artifactoryrsquos OSS
Groovy 24 Java 6 Java 8 Java 9 snapshot groovy-nio Java 7 invokeDynamic Java 7+ Java 8
Groovy CI Java Groovy 10000 Java Groovy
112 Maven Repository
Groovy maven repositories JCenter maven repository
3
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
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groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
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groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
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groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
Contents
1 311 Groovy 312 Groovy 5
2 Indices and tables 25
i
ii
groovys Documentation 100
Contents
Contents 1
groovys Documentation 100
2 Contents
CHAPTER 1
11 Groovy
111
Groovy windows Mac OSX Linux Cygwin GVM Groovy Groovy
bull zipBinary Release | Source Release
bull JavaDoc and zipped online documentation
bull amp amp Distribution bundle
invokedynamic
Groovy (snapshot) CI Artifactoryrsquos OSS
Groovy 24 Java 6 Java 8 Java 9 snapshot groovy-nio Java 7 invokeDynamic Java 7+ Java 8
Groovy CI Java Groovy 10000 Java Groovy
112 Maven Repository
Groovy maven repositories JCenter maven repository
3
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
6 Chapter 1
groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
8 Chapter 1
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
12 Groovy 9
groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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groovys Documentation 100
assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
14 Chapter 1
groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
12 Groovy 15
groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
16 Chapter 1
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
ii
groovys Documentation 100
Contents
Contents 1
groovys Documentation 100
2 Contents
CHAPTER 1
11 Groovy
111
Groovy windows Mac OSX Linux Cygwin GVM Groovy Groovy
bull zipBinary Release | Source Release
bull JavaDoc and zipped online documentation
bull amp amp Distribution bundle
invokedynamic
Groovy (snapshot) CI Artifactoryrsquos OSS
Groovy 24 Java 6 Java 8 Java 9 snapshot groovy-nio Java 7 invokeDynamic Java 7+ Java 8
Groovy CI Java Groovy 10000 Java Groovy
112 Maven Repository
Groovy maven repositories JCenter maven repository
3
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
6 Chapter 1
groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
8 Chapter 1
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
12 Groovy 9
groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
12 Chapter 1
groovys Documentation 100
assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
14 Chapter 1
groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
12 Groovy 15
groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
16 Chapter 1
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
Contents
Contents 1
groovys Documentation 100
2 Contents
CHAPTER 1
11 Groovy
111
Groovy windows Mac OSX Linux Cygwin GVM Groovy Groovy
bull zipBinary Release | Source Release
bull JavaDoc and zipped online documentation
bull amp amp Distribution bundle
invokedynamic
Groovy (snapshot) CI Artifactoryrsquos OSS
Groovy 24 Java 6 Java 8 Java 9 snapshot groovy-nio Java 7 invokeDynamic Java 7+ Java 8
Groovy CI Java Groovy 10000 Java Groovy
112 Maven Repository
Groovy maven repositories JCenter maven repository
3
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
6 Chapter 1
groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
8 Chapter 1
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
12 Groovy 9
groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
10 Chapter 1
groovys Documentation 100
list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
12 Chapter 1
groovys Documentation 100
assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
14 Chapter 1
groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
12 Groovy 15
groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
16 Chapter 1
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
2 Contents
CHAPTER 1
11 Groovy
111
Groovy windows Mac OSX Linux Cygwin GVM Groovy Groovy
bull zipBinary Release | Source Release
bull JavaDoc and zipped online documentation
bull amp amp Distribution bundle
invokedynamic
Groovy (snapshot) CI Artifactoryrsquos OSS
Groovy 24 Java 6 Java 8 Java 9 snapshot groovy-nio Java 7 invokeDynamic Java 7+ Java 8
Groovy CI Java Groovy 10000 Java Groovy
112 Maven Repository
Groovy maven repositories JCenter maven repository
3
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
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new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
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groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
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groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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groovys Documentation 100
assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
CHAPTER 1
11 Groovy
111
Groovy windows Mac OSX Linux Cygwin GVM Groovy Groovy
bull zipBinary Release | Source Release
bull JavaDoc and zipped online documentation
bull amp amp Distribution bundle
invokedynamic
Groovy (snapshot) CI Artifactoryrsquos OSS
Groovy 24 Java 6 Java 8 Java 9 snapshot groovy-nio Java 7 invokeDynamic Java 7+ Java 8
Groovy CI Java Groovy 10000 Java Groovy
112 Maven Repository
Groovy maven repositories JCenter maven repository
3
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
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new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
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groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
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groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
Gradle Maven Explanationorgcodehausgroovygroovy245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovyltartifactIdgtltversiongt245ltversiongt
Just the core of groovy without themodules (see below)
orgcodehausgroovygroovy- $mod-ule245lsquo
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-$moduleltartifactIdgt ltver-siongt245ltversiongt
Example ltartifactIdgtgroovy-sqlltartifactIdgt
orgcodehausgroovygroovy-all245
ltgroupIdgtorgcodehausgroovyltgroupIdgtltartifactIdgtgroovy-allltartifactIdgtltversiongt245ltversiongt
InvokeDynamic jars Gradle indy Maven ltclassifiergtindyltclassifiergt
113 GVM (the Groovy enVironment Manager)
GVM (Mac OSX Linux Cygwin Solaris or FreeBSD) Bash Groovy
terminal
$ curl -s getgvmtoolnet | bash
terminal
$ source $HOMEgvmbingvm-initsh
Groovy
$ gvm install groovy
$ groovy -version
114 Groovy
Mac OS X
MacOS MacPorts
sudo port install groovy
MacOS Homebrew
brew install groovy
Windows
Windows NSIS Windows installer
4 Chapter 1
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
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new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
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groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
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Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
Other Distributions
You may download other distributions of Groovy from this site
Source Code
GitHub
115 IDE plugin
IDE IDE
116
Groovy
bull
bull GROOVY_HOME
bull GROOVY_HOMEbin PATH
bull JAVA_HOME JDK OS X LibraryJavaHome unix
usrjava Ant Maven
Groovy
groovysh
Groovy shell Groovy Swing interactive console
groovyConsole
Groovy script
groovy SomeScript
12 Groovy
121 Working with IO
Groovy IO JAVA Groovy Groovy reader
bull the javaioFile class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioFilehtml
bull the javaioInputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioInputStreamhtml
bull the javaioOutputStream class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioOutputStreamhtml
bull the javaioReader class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioReaderhtml
bull the javaioWriter class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaioWriterhtml
bull the javaniofilePath class httpdocsgroovy-langorglatesthtmlgroovy-jdkjavaniofilePathhtml
12 Groovy 5
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
6 Chapter 1
groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
8 Chapter 1
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
12 Groovy 9
groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
GDK API
new File(baseDir haikutxt)eachLine line -gtprintln line
eachLine Groovy File
new File(baseDir haikutxt)eachLine line nb -gtprintln Line $nb $line
eachLine Groovy IO
Reader Groovy reader
def count = 0 MAXSIZE = 3new File(baseDirhaikutxt)withReader reader -gt
while (readerreadLine()) if (++count gt MAXSIZE)
throw new RuntimeException(Haiku should only have 3 verses)
list
def list = new File(baseDir haikutxt)collect it
as
def array = new File(baseDir haikutxt) as String[]
byte[]
Groovy
byte[] contents = filebytes
IO Groovy
InputStream
def is = new File(baseDirhaikutxt)newInputStream() do something isclose()
inputstream Groovy withInputStream
new File(baseDirhaikutxt)withInputStream stream -gt do something
Writer
6 Chapter 1
groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
8 Chapter 1
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
12 Groovy 9
groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
10 Chapter 1
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
16 Chapter 1
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
new File(baseDirhaikutxt)withWriter(utf-8) writer -gtwriterwriteLine Into the ancient pondwriterwriteLine A frog jumpswriterwriteLine Waterrsquos sound
ltlt
new File(baseDirhaikutxt) ltlt Into the ancient pondA frog jumpsWaterrsquos sound
Writer
filebytes = [662211]
def os = new File(baseDirdatabin)newOutputStream() do something osclose()
withOutputStream
new File(baseDirdatabin)withOutputStream stream -gt do something
Groovy
direachFile file -gt lt1gtprintln filename
direachFileMatch(~txt) file -gt lt2gt
println filename
lt1gt
lt2gt
eachFileRecurse
direachFileRecurse file -gt lt1gtprintln filename
direachFileRecurse(FileTypeFILES) file -gt lt2gtprintln filename
lt1gt
lt2gt
traverse
dirtraverse file -gtif (filedirectory ampamp filename==bin)
FileVisitResultTERMINATE lt1gt
12 Groovy 7
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
8 Chapter 1
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
12 Groovy 9
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Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
12 Chapter 1
groovys Documentation 100
assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
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groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
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groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
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list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
else println filenameFileVisitResultCONTINUE lt2gt
lt1gt bin
lt2gt
Data amp objects
JAVA javaioDataOutputStream amp javaioDataInputStream Groovy
boolean b = trueString message = Hello from Groovy Serialize data into a filefilewithDataOutputStream out -gt
outwriteBoolean(b)outwriteUTF(message)
Then read it backfilewithDataInputStream input -gt
assert inputreadBoolean() == bassert inputreadUTF() == message
Serializable
Person p = new Person(nameBob age76) Serialize data into a filefilewithObjectOutputStream out -gt
outwriteObject(p) Then read it backfilewithObjectInputStream input -gt
def p2 = inputreadObject()assert p2name == pnameassert p2age == page
Groovy reader Groovy exxcute()
def process = ls -lexecute() lt1gtprintln Found text $processtext lt2gt
lt1gt ls
lt2gt
execute() javalangProcess inouterr streams
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def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
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Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
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assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
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groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
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bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
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list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
def process = ls -lexecute() lt1gtprocessineachLine line -gt lt2gt
println line lt3gt
lt1gt
lt2gt
lt3gt
out
shell windows
def process = direxecute()println $processtext
IOException Cannot run program ldquodirrdquo CreateProcess error=2 The system cannot find the file specified dir Cre-ateProcess error=2
dir cmdexe
def process = cmd c direxecute()println $processtext
javalangProcess javadoc
Because some native platforms only provide limited buffer size for standard input and output streams failure topromptly write the input stream or read the output stream of the subprocess may cause the subprocess to block andeven deadlock
Groovy
def p = rm -f footmpexecute([] tmpDir)pconsumeProcessOutput()pwaitFor()
consumeProcessOutput StringBuffer InputStream OutputStream GDK API forjavalangProcess
pipeTo
Pipes in action
proc1 = lsexecute()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc1 | proc2 | proc3 | proc4proc4waitFor()if (proc4exitValue())
println proc4errtext else
println proc4text
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Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
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assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
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groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
16 Chapter 1
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
Consuming errors
def sout = new StringBuilder()def serr = new StringBuilder()proc2 = tr -d oexecute()proc3 = tr -d eexecute()proc4 = tr -d iexecute()proc4consumeProcessOutput(sout serr)proc2 | proc3 | proc4[proc2 proc3]each itconsumeProcessErrorStream(serr) proc2withWriter writer -gt
writer ltlt testfilegroovyproc4waitForOrKill(1000)println Standard output $soutprintln Standard error $serr
122 Working with collections
Groovy lists maps ranges Java Groovy
Lists
lists []
def list = [5 6 7 8]assert listget(2) == 7assert list[2] == 7assert list instanceof javautilList
def emptyList = []assert emptyListsize() == 0emptyListadd(5)assert emptyListsize() == 1
list javautilList lists lists
def list1 = [a b c]construct a new list seeded with the same items as in list1def list2 = new ArrayListltStringgt(list1)
assert list2 == list1 == checks that each corresponding element is the same
clone() can also be calleddef list3 = list1clone()assert list3 == list1
list
def list = [5 6 7 8]assert listsize() == 4assert listgetClass() == ArrayList the specific kind of list being used
assert list[2] == 7 indexing starts at 0assert listgetAt(2) == 7 equivalent method to subscript operator []assert listget(2) == 7 alternative method
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list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
12 Groovy 13
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
list[2] = 9assert list == [5 6 9 8] trailing comma OK
listputAt(2 10) equivalent method to [] when value being changedassert list == [5 6 10 8]assert listset(2 11) == 10 alternative method that returns old valueassert list == [5 6 11 8]
assert [a 1 a a 25 25f 25d hello 7g null 9 as byte]objects can be of different types duplicates allowed
assert [1 2 3 4 5][-1] == 5 use negative indices to count from the endassert [1 2 3 4 5][-2] == 4assert [1 2 3 4 5]getAt(-2) == 4 getAt() available with negative indextry
[1 2 3 4 5]get(-2) but negative index not allowed with get()assert false
catch (e) assert e instanceof ArrayIndexOutOfBoundsException
assert [] an empty list evaluates as false
all other lists irrespective of contents evaluate as trueassert [1] ampamp [a] ampamp [0] ampamp [00] ampamp [false] ampamp [null]
each eachWithIndex code-block groovy
[1 2 3]each println ldquoItem $itrdquo it is an implicit parameter corresponding to the current element
[rsquoarsquo lsquobrsquo lsquocrsquo]eachWithIndex it i -gt it is the current element while i is the index
println ldquo$i $itrdquo
mapping Groovy collect
assert [1 2 3]collect it 2 == [2 4 6]
shortcut syntax instead of collectassert [1 2 3]multiply(2) == [1 2 3]collect itmultiply(2)
def list = [0] it is possible to give `collect` the list which collects the elementsassert [1 2 3]collect(list) it 2 == [0 2 4 6]assert list == [0 2 4 6]
Groovy
12 Groovy 11
groovys Documentation 100
assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
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list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
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bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
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list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
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Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
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assert [1 2 3]find it gt 1 == 2 find 1st element matching criteriaassert [1 2 3]findAll it gt 1 == [2 3] find all elements matching critieriaassert [a b c d e]findIndexOf find index of 1st element matching criteria
it in [c e g] == 2
assert [a b c d c]indexOf(c) == 2 index returnedassert [a b c d c]indexOf(z) == -1 index -1 means value not in listassert [a b c d c]lastIndexOf(c) == 4
assert [1 2 3]every it lt 5 returns true if all elements match the predicateassert [1 2 3]every it lt 3 assert [1 2 3]any it gt 2 returns true if any element matches the predicateassert [1 2 3]any it gt 3
assert [1 2 3 4 5 6]sum() == 21 sum anything with a plus() methodassert [a b c d e]sum
it == a 1 it == b 2 it == c 3 it == d 4 it == e 5 0 custom value to use in sum
== 15assert [a b c d e]sum ((char) it) - ((char) a) == 10assert [a b c d e]sum() == abcdeassert [[a b] [c d]]sum() == [a b c d]
an initial value can be providedassert []sum(1000) == 1000assert [1 2 3]sum(1000) == 1006
assert [1 2 3]join(-) == 1-2-3 String joiningassert [1 2 3]inject(counting )
str item -gt str + item reduce operation == counting 123assert [1 2 3]inject(0) count item -gt
count + item == 6
Groovy
def list = [9 4 2 10 5]assert listmax() == 10assert listmin() == 2
we can also compare single characters as anything comparableassert [x y a z]min() == a
we can use a closure to specify the sorting behaviourdef list2 = [abc z xyzuvw Hello 321]assert list2max itsize() == xyzuvwassert list2min itsize() == z
Comparator
Comparator mc = a b -gt a == b 0 (a lt b -1 1)
def list = [7 4 9 -6 -1 11 2 3 -9 5 -13]assert listmax(mc) == 11assert listmin(mc) == -13
Comparator mc2 = a b -gt a == b 0 (Mathabs(a) lt Mathabs(b)) -1 1
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
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list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
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bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
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list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
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Indices and tables
bull genindex
bull modindex
bull search
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- Groovy
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- Indices and tables
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assert listmax(mc2) == -13assert listmin(mc2) == -1
assert listmax a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -13assert listmin a b -gt aequals(b) 0 Mathabs(a) lt Mathabs(b) -1 1 == -1
[] ltlt
def list = []assert listempty
list ltlt 5assert listsize() == 1
list ltlt 7 ltlt i ltlt 11assert list == [5 7 i 11]
list ltlt [m o]assert list == [5 7 i 11 [m o]]
first item in chain of ltlt is target listassert ([1 2] ltlt 3 ltlt [4 5] ltlt 6) == [1 2 3 [4 5] 6]
using leftShift is equivalent to using ltltassert ([1 2 3] ltlt 4) == ([1 2 3]leftShift(4))
assert [1 2] + 3 + [4 5] + 6 == [1 2 3 4 5 6] equivalent to calling the `plus` methodassert [1 2]plus(3)plus([4 5])plus(6) == [1 2 3 4 5 6]
def a = [1 2 3]a += 4 creates a new list and assigns it to `a`a += [5 6]assert a == [1 2 3 4 5 6]
assert [1 [222 333] 456] == [1 222 333 456]assert [[1 2 3]] == [1 2 3]assert [1 [2 3 [4 5] 6] 7 [8 9]]flatten() == [1 2 3 4 5 6 7 8 9]
def list = [1 2]listadd(3)listaddAll([5 4])assert list == [1 2 3 5 4]
list = [1 2]listadd(1 3) add 3 just before index 1assert list == [1 3 2]
listaddAll(2 [5 4]) add [54] just before index 2assert list == [1 3 5 4 2]
list = [a b z e u v g]
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list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
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def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
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bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
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list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
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Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
list[8] = x the [] operator is growing the list as needed nulls inserted if requiredassert list == [a b z e u v g null x]
ltlt + list
Groovy
assert [abcbb] - c == [abbb]assert [abcbb] - b == [ac]assert [abcbb] - [bc] == [a]
def list = [1234321]list -= 3 creates a new list by removing `3` from the original oneassert list == [12421]assert ( list -= [24] ) == [11]
def list = [123456221]assert listremove(2) == 3 remove the third element and return itassert list == [12456221]
remove
def list= [abcbb]assert listremove(c) remove c and return true because element removedassert listremove(b) remove first b and return true because element removed
assert listremove(z) return false because no elements removedassert list == [abb]
clear
def list= [a2c4]listclear()assert list == []
Set operations
Groovy
assert a in [abc] returns true if an element belongs to the listassert [abc]contains(a) equivalent to the `contains` method in Javaassert [134]containsAll([14]) `containsAll` will check that all elements are found
assert [12333345]count(3) == 4 count the number of elements which have some valueassert [12333345]count
it2==0 count the number of elements which match the predicate == 2
assert [124681012]intersect([136912]) == [1612]
assert [123]disjoint( [469] ) assert [123]disjoint( [246] )
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Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
Groovy
assert [6 3 9 2 7 1 5]sort() == [1 2 3 5 6 7 9]
def list = [abc z xyzuvw Hello 321]assert listsort
itsize() == [z abc 321 Hello xyzuvw]
def list2 = [7 4 -6 -1 11 2 3 -9 5 -13]assert list2sort a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1 ==
[-1 2 3 4 5 -6 7 -9 11 -13]
Comparator mc = a b -gt a == b 0 Mathabs(a) lt Mathabs(b) -1 1
JDK 8+ only list2sort(mc) assert list2 == [-1 2 3 4 5 -6 7 -9 11 -13]
def list3 = [6 -3 9 2 -7 1 5]
Collectionssort(list3)assert list3 == [-7 -3 1 2 5 6 9]
Collectionssort(list3 mc)assert list3 == [1 2 -3 5 6 -7 9]
Groovy
assert [1 2 3] 3 == [1 2 3 1 2 3 1 2 3]assert [1 2 3]multiply(2) == [1 2 3 1 2 3]assert CollectionsnCopies(3 b) == [b b b]
nCopies from the JDK has different semantics than multiply for listsassert CollectionsnCopies(2 [1 2]) == [[1 2] [1 2]] not [1212]
123 Maps
Map literals
Groovy [] map
def map = [name Gromit likes cheese id 1234]assert mapget(name) == Gromitassert mapget(id) == 1234assert map[name] == Gromitassert map[id] == 1234assert map instanceof javautilMap
def emptyMap = []assert emptyMapsize() == 0
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groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
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assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
emptyMapput(foo 5)assert emptyMapsize() == 1assert emptyMapget(foo) == 5
Map key String [a1] [rsquoarsquo1] Map keys are strings by default [a1] is equivalent to [rsquoarsquo1] a a map key
def a = Bobdef ages = [a 43]assert ages[Bob] == null `Bob` is not foundassert ages[a] == 43 because `a` is a literal
ages = [(a) 43] now we escape `a` by using parenthesisassert ages[Bob] == 43 and the value is found
Map clone
def map = [simple 123complex [a 1 b 2]
]def map2 = mapclone()assert map2get(simple) == mapget(simple)assert map2get(complex) == mapget(complex)map2get(complex)put(c 3)assert mapget(complex)get(c) == 3
map
Map property notation
Maps beans key map
def map = [name Gromit likes cheese id 1234]assert mapname == Gromit can be used instead of mapget(Gromit)assert mapid == 1234
def emptyMap = []assert emptyMapsize() == 0emptyMapfoo = 5assert emptyMapsize() == 1assert emptyMapfoo == 5
mapfoo map key foo fooclass null map class key key class getClass()
def map = [name Gromit likes cheese id 1234]assert mapclass == nullassert mapget(class) == nullassert mapgetClass() == LinkedHashMap this is probably what you want
map = [1 a(true) p(false) q(null) xnull z]
assert mapcontainsKey(1) 1 is not an identifier so used as isassert maptrue == nullassert mapfalse == nullassert mapget(true) == p
16 Chapter 1
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
assert mapget(false) == qassert mapnull == zassert mapget(null) == x
maps
Groovy each eachWithIndex map map
def map = [Bob 42Alice 54Max 33
]
`entry` is a map entrymapeach entry -gt
println Name $entrykey Age $entryvalue
`entry` is a map entry `i` the index in the mapmapeachWithIndex entry i -gt
println $i - Name $entrykey Age $entryvalue
Alternatively you can use key and value directlymapeach key value -gt
println Name $key Age $value
Key value and i as the index in the mapmapeachWithIndex key value i -gt
println $i - Name $key Age $value
Map
map put putAll
def defaults = [1 a 2 b 3 c 4 d]def overrides = [2 z 5 x 13 x]
def result = new LinkedHashMap(defaults)resultput(15 t)result[17] = uresultputAll(overrides)assert result == [1 a 2 z 3 c 4 d 5 x 13 x 15 t 17 u]
clear map
def m = [1a 2b]assert mget(1) == amclear()assert m == []
Maps object equals hashcode hash code key GString map key GString hash code String hash code
12 Groovy 17
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def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
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assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
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assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
def key = some keydef map = []def gstringKey = $keytoUpperCase()mapput(gstringKeyvalue)assert mapget(SOME KEY) == null
def map = [1a 2b 3c]
def entries = mapentrySet()entrieseach entry -gt
assert entrykey in [123]assert entryvalue in [abc]
def keys = mapkeySet()assert keys == [123] as Set
Mutating values returned by the view (be it a map entry a key or a value) is highly discouraged because success ofthe operation directly depends on the type of the map being manipulated In particular Groovy relies on collectionsfrom the JDK that in general make no guarantee that a collection can safely be manipulated through keySet entrySetor values
Groovy httpwwwgroovy-langorggroovy-dev-kithtmlList-Filtering[list] The Groovy development kit containsfiltering searching and collecting methods similar to those found for lists
def people = [1 [nameBob age 32 gender M]2 [nameJohnny age 36 gender M]3 [nameClaire age 21 gender F]4 [nameAmy age 54 genderF]
]
def bob = peoplefind itvaluename == Bob find a single entrydef females = peoplefindAll itvaluegender == F
both return entries but you can use collect to retrieve the ages for exampledef ageOfBob = bobvalueagedef agesOfFemales = femalescollect
itvalueage
assert ageOfBob == 32assert agesOfFemales == [2154]
but you could also use a keypair value as the parameters of the closuresdef agesOfMales = peoplefindAll id person -gt
persongender == Mcollect id person -gt
personageassert agesOfMales == [32 36]
`every` returns true if all entries match the predicateassert peopleevery id person -gt
personage gt 18
`any` returns true if any entry matches the predicate
18 Chapter 1
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
assert peopleany id person -gtpersonage == 54
assert [a 7 b [2 3]]groupBy itclass
== [(String) [a b](Integer) [7](ArrayList) [[2 3]]
]
assert [[name Clark city London] [name Sharma city London][name Maradona city LA] [name Zhang city HK][name Ali city HK] [name Liu city HK]
]groupBy itcity == [London [[name Clark city London]
[name Sharma city London]]LA [[name Maradona city LA]]HK [[name Zhang city HK]
[name Ali city HK][name Liu city HK]]
]
Ranges
Ranges Ranges List Range javautilList Ranges Ranges lt
an inclusive rangedef range = 58assert rangesize() == 4assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
lets use a half-open rangerange = 5lt8assert rangesize() == 3assert rangeget(2) == 7assert range[2] == 7assert range instanceof javautilListassert rangecontains(5)assert rangecontains(8)
get the end points of the range without using indexesrange = 110assert rangefrom == 1assert rangeto == 10
int ranges java
Ranges javalangComparable java next() previous() String
an inclusive rangedef range = ad
12 Groovy 19
groovys Documentation 100
assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
20 Chapter 1
groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
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list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
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assert rangesize() == 4assert rangeget(2) == cassert range[2] == cassert range instanceof javautilListassert rangecontains(a)assert rangecontains(d)assert rangecontains(e)
for
for (i in 110) println Hello $i
Groovy each
(110)each i -gtprintln Hello $i
Ranges switch
switch (years) case 110 interestRate = 0076 breakcase 1125 interestRate = 0052 breakdefault interestRate = 0037
lists maps Groovy
def listOfMaps = [[a 11 b 12] [a 21 b 22]]assert listOfMapsa == [11 21] GPath notationassert listOfMapsa == [11 21] spread dot notation
listOfMaps = [[a 11 b 12] [a 21 b 22] null]assert listOfMapsa == [11 21 null] caters for null valuesassert listOfMapsa == listOfMapscollect ita equivalent notation But this will only collect non-null valuesassert listOfMapsa == [1121]
Spread operator putAll
assert [ z 900
[a 100 b 200] a 300] == [a 300 b 200 z 900]spread map notation in map definitionassert [ [3 3 [5 5]] 7 7] == [3 3 5 5 7 7]
def f = [1 u 2 v 3 w] assert [ f() 10 zz] == [1 u 10 zz 2 v 3 w]spread map notation in function argumentsf = map -gt mapc assert f( [a 10 b 20 c 30] e 50) == 30
f = m i j k -gt [m i j k] using spread map notation with mixed unnamed and named argumentsassert f(e 100 [4 5] [a 10 b 20 c 30] 6) ==
[[e 100 b 20 c 30 a 10] 4 5 6]
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assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
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bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
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bull modindex
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- Groovy
- Groovy
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- Indices and tables
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groovys Documentation 100
assert [1 3 5] == [a few words]size()
class Person String nameint age
def persons = [new Person(nameHugo age17) new Person(nameSandraage19)]assert [17 19] == personsage
listsmapsarrays
def text = nice cheese gromitdef x = text[2]
assert x == cassert xclass == String
def sub = text[510]assert sub == cheese
def list = [10 11 12 13]def answer = list[23]assert answer == [1213]
ranges
list = 100200sub = list[1 3 2025 33]assert sub == [101 103 120 121 122 123 124 125 133]
list = [axxd]list[12] = [bc]assert list == [abcd]
List array String
text = nice cheese gromitx = text[-1]assert x ==
def name = text[-7-2]assert name == gromit
text = nice cheese gromitname = text[31]assert name == eci
lists maps ranges Groovy
Groovy API
bull methods added to Iterable can be found here
12 Groovy 21
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
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bull modindex
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- Groovy
- Groovy
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- Indices and tables
-
groovys Documentation 100
bull methods added to Iterator can be found here
bull methods added to Collection can be found here
bull methods added to List can be found here
bull methods added to Map can be found here
124 Handy utilities ()
ConfigSlurper
ConfigSlurper Groovy script Java properties ConfigSlurper
def config = new ConfigSlurper()parse(appdate = new Date() lt1gtappage = 42app lt2gt
name = Test$42
)
assert configappdate instanceof Dateassert configappage == 42assert configappname == Test42
lt1gt
lt2gt
parse groovyutilConfigObject ConfigObject javautilMap ConfigObject null
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42appname = Test$42
)
assert configtest = null lt1gt
lt1gt configtest ConfigObject
def config = new ConfigSlurper()parse(apppersonage = 42
)
assert configapppersonage == 42
ConfigSlurper environments ConfigSlurper(String)
def config = new ConfigSlurper(development)parse(environments
development appport = 8080
test appport = 8082
22 Chapter 1
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production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
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bull modindex
bull search
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- Groovy
- Groovy
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- Indices and tables
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groovys Documentation 100
production appport = 80
)
assert configappport == 8080
ConfigSlurper environments environments registerConditionalBlock environments
def slurper = new ConfigSlurper()slurperregisterConditionalBlock(myProject developers) lt1gt
def config = slurperparse(sendMail = true
myProject developers
sendMail = false
)
assert configsendMail
lt1gt ConfigSlurper
Java toProperties ConfigObject javautilProperties properties Properties
def config = new ConfigSlurper()parse(appdate = new Date()appage = 42app
name = Test$42
)
def properties = configtoProperties()
assert propertiesappdate instanceof Stringassert propertiesappage == 42assert propertiesappname == Test42
Expando
Expando
def expando = new Expando()expandoname = John
assert expandoname == John
def expando = new Expando()expandotoString = -gt John expandosay = String s -gt John says $s
assert expando as String == Johnassert expandosay(Hi) == John says Hi
12 Groovy 23
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
groovys Documentation 100
list map and set
Groovy lists map sets javabeansPropertyChangeEvent
PropertyChangeEvent ObservableListElementAddedEvent
def event lt1gtdef listener =
if (it instanceof ObservableListElementEvent) lt2gtevent = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableList lt3gtobservableaddPropertyChangeListener(listener) lt4gt
observableadd 42 lt5gt
assert event instanceof ObservableListElementAddedEvent
def elementAddedEvent = event as ObservableListElementAddedEventassert elementAddedEventchangeType == ObservableListChangeTypeADDEDassert elementAddedEventindex == 3assert elementAddedEventoldValue == nullassert elementAddedEventnewValue == 42
lt1gt PropertyChangeEventListener
lt2gt ObservableListElementEvent
lt3gt
lt4gt
lt5gt
ObservableListElementAddedEvent PropertyChangeEvent clear()ObservableListElementClearedEvent
def eventdef listener =
if (it instanceof ObservableListElementEvent) event = it
as PropertyChangeListener
def observable = [1 2 3] as ObservableListobservableaddPropertyChangeListener(listener)
observableclear()
assert event instanceof ObservableListElementClearedEvent
def elementClearedEvent = event as ObservableListElementClearedEventassert elementClearedEventvalues == [1 2 3]assert observablesize() == 0
ObservableMap and ObservableSet ObservableList
24 Chapter 1
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-
CHAPTER 2
Indices and tables
bull genindex
bull modindex
bull search
25
- Groovy
- Groovy
-
- Indices and tables
-