java development environment and review of java

Java development environment and Review of Java

EclipseTM Intergrated Development Environment (IDE) Running Eclipse:

Warning: Never check the “Use this as the default and do not ask again” box.

The importance of workspace

This is where you will find all your java files. You can switch from one workspace to

another. You need to define the workspace first

(where you want to put your files) before click on OK

EclipseTM tutorial

Perspective is a set of related Views (windows)

that enable a development specialist to perform

specific tasks

Setting up preferences in Eclipse

If you did not download the JDK earlier in this tutorial, and your existing JRE does not appear in the “Installed JREs” preference, you must add it yourself.

Setting up preferences in Eclipse

Setting up preferences in Eclipse

Create an Eclipse project

From the Eclipse menu bar select File, New, Project to start the “New Project” wizard.Select “Java Project” and click “Next”.

Create an Eclipse project

Create a Java package

Structure in dot format:

for example: com.tm.tutorial.main

Create Java classes

Create Application class under com.tm.tutorial.main package

Create Java classes

Create Application class under com.tm.tutorial.main package

Implementation of Java class

Implementation of Java class

Generating setters and getters for attributes

Implementation of Java class

Generating constructors

Implementation of Java class

Generating constructors

Compile Java Application

Compile Java Application

Run the application

Run the application

Run the application

Run the application

Run Application (Shorter way)

Project 1 discussion

Algorithm for Main class

Assign a file nameAssign a file name

Create a report objectCreate a report object

Call a method from Report class to produce report from the given data file

Call a method from Report class to produce report from the given data file

Structure of Report class

Report object

-inFile

-currentBook, nextBook….

FileInputFileInput

Book

+printReport-processBook-processGenre-columnHeadings-padL-padR

Datamembers

Methods

Algorithm for printing a report (Report.java)

Open fileOpen file

Printing headingPrinting heading

Read a recordRead a record

processing genre*processing genre*

Print footer of the report

Print footer of the report

Record != null ?Record != null ?

true

false

Algorithm for process a book and a genre

currentBook = record just readCurrent genre = genre of the current book

currentBook = record just readCurrent genre = genre of the current book

Print information about a bookPrint information about a book

Read another bookRead another book

Total price for each genre += price of the current book

Total price for each genre += price of the current book

Start a new genre and go back to processing a new genre

Start a new genre and go back to processing a new genre

Is another book has the same genre ?

Is another book has the same genre ?

true

false

Class exercise

Class Object Primitive Data Type If, Switch While, Do-While

Review of Java fundamentalsTemplate for Class Definition

class {

}

Import StatementsImport Statements

Class CommentClass Comment

Class NameClass Name

Data MembersData Members

Methods(incl. Constructor)

Methods(incl. Constructor)

Review of Java fundamentalsTemplate for Class Definition

class {

}

Import StatementsImport Statements

Class CommentClass Comment

Class NameClass Name

Data MembersData Members

Methods(incl. Constructor)

Methods(incl. Constructor)

Numeric data

Variable declaration:

<data type> <variable_name>;

If more than one variable has the same data type:

<data type> <name1>, <name2>..;

Six numerical data types

byte: -128 to 127 short:-32768 to 32767 (-215 to 215-1) int: -231 to 231-1 long: -263 to 263-1 float: -3.4E+38 to 3.4E+38 double:-1.797E+308 to 1.797E+308

Assignment statement

<variable name> = <expression>;

Example:

x =2*5+6-1;

Variable names

It must be a legal identifier which is an unlimited series of characters that begins with a letter.

It must not be a keyword, a boolean literal (true or false), or the reserved word null.

It must be unique within its scope.

Variable name (cont.)

Legal identifier:be composed of letters, numbers, _ and $. Identifiers may only begin with a letter, _, or $.

Keyword:

http://java.sun.com/docs/books/tutorial/java/nutsandbolts/_keywords.html

Variable names begin with a lowercase letter Class names begin with an uppercase letter

Constant and variables

Constant: Value it contains doesn’t change

final int MONTHS_IN_YEAR = 12;

Variables: Value it contains may vary

double loanAmount; loanAmount =0; loanAmount = 1000.99;

Integer division and type casting Integer division:

Integer/integer = integer, 7/2 = 3 Integer/double = double, 7/2.0 = 3.5 Double/integer = double, 7.0/2 = 3.5

Type casting: a process that converts a value of one data type to another data type.

Implicit casting

Explicit casting

Type casting (cont.)

Implicit casting: Operand is converted from a lower to a higher

precision Higher precision: a data type with a larger range

of values Double has a higher precision than float Int has a higher precision than short

Operand: can be a constant, variable, method call or another arithmetic expression

Type casting (cont.)

Explicit casting (<data type>) <expression> Example:

float result;

result = (float) ((3+5)/6);

and

result = ((float) (5+3))/6;

if (<boolean expression>) <block>;else <block>;

Simple Choice Statement

if (<boolean expression>) single statement;else single statement;

Boolean expression

Boolean expression: is a conditional expression that is evaluated to either true or false.

Conditional expression: is a three part expression:<exp.> <relational operators><exp.>

Boolean expressions can be combined by boolean operators

Relational Operators

Expression Meaninga == b Is a equal to b?a != b Is a not equal to b?a > b Is a greater than b?a < b Is a less than b?a >= b Is a greater than or equal to b?a <= b Is a less than or equal to b?

Boolean operators

&& means AND

|| means OR

! means NOT

The While Loop

while(<boolean expression>){

// Repeat multiple statements.

statement 1

statement 2

statement 3

...

}

The Do Loopdo{ // Repeat multiple statements. statement 1 statement 2 statement 3 ...} while(<boolean expression);

•Note that the statements in the body of the loop are always executed at least one.•Note the final semicolon, which is required.

The For-Loop Outline// Repeat multiple statements.for(initialization; condition; post-body update){ // Statements to be repeated. statement 1 statement 2 statement 3 ...}

•Commonly used with increment and decrement operators.

Increment and Decrement Used as a shorthand for add-one-to and

subtract-one-from: value = value+1; value += 1; value++;

Prefix and postfix forms: ++value; --value; value--;

Attributes (Data Member) Declaration

<modifiers> <data type> <name> ;

private String ownerName ;

ModifiersModifiers Data TypeData Type NameName

Note: There’s only one modifier in this example.

Note: There’s only one modifier in this example.

Method Declaration

<modifier> <return type> <method name> ( <parameters> ){

<statements>

}

public void setOwnerName ( String name ) {

ownerName = name;

}

StatementsStatements

ModifierModifier Return TypeReturn Type Method NameMethod Name ParameterParameter

Constructor A constructor is a special method that is executed when a new

instance of the class is created.

public <class name> ( <parameters> ){ <statements> }

public Bicycle ( ) {

ownerName = “Unassigned”;

}StatementsStatements

ModifierModifier Class NameClass Name ParameterParameter

Arguments and Parameters

An argument is a value we pass to a method. A parameter is a placeholder in the called method to

hold the value of the passed argument.

class Account {

. . .

public void add(double amt) {

balance = balance + amt; }

. . . }

class Sample {

public static void main(String[] arg) { Account acct = new Account(); . . . acct.add(400); . . . }

. . . } argument

Arguments and Parameters

An argument is a value we pass to a method. A parameter is a placeholder in the called method to

hold the value of the passed argument.

class Account {

. . .

public void add(double amt) {

balance = balance + amt; }

. . . }

class Sample {

public static void main(String[] arg) { Account acct = new Account(); . . . acct.add(400); . . . }

. . . }

parameter

Algorithm for Main class

Assign a file nameAssign a file name

Create a report objectCreate a report object

Call a method from Report class to produce report from the given data file

Call a method from Report class to produce report from the given data file

Algorithm for printing a report (Report.java)

Open fileOpen file

Printing headingPrinting heading

Read a recordRead a record

processing a movie*processing a movie*

Print footer of the report

Print footer of the report

Record != null ?Record != null ?

true

false

Algorithm for process a movie and a genre

currentMovie = record just readCurrent genre = genre of the current movie

currentMovie = record just readCurrent genre = genre of the current movie

Print information about a moviePrint information about a movie

Read another movieRead another movie

Total price for each genre += price of the current movie

Total price for each genre += price of the current movie

Start a new genre and go back to processing a new genre

Start a new genre and go back to processing a new genre

Is another movie has the same genre ?

Is another movie has the same genre ?

true

false