java vs csharp

7/31/2019 Java vs Csharp

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Java vs C#

Getting started code

Java

Java is a strongly-typed object-oriented languagedeveloped by SUN.

class Hello{

public static void

main(String[] args) {System.out.println("hello

, world");}

}//you must save the file with.java extension//from command line to compile it>javac Hello.java//generate a Hello.class file andrun it>java Hellohello, world

C#

C# is a strongly-typed object-orientedlanguagedeveloped by Microsoft.

class Hello{

static void Main() {

System.Console.WriteLine("hello, world");

}}//by convention, save the file with.cs extension//from command line to compile it>csc Hello.cs//generate a Hello.exe file and run it>Hellohello, world

Java vs C#

Keywords & Reserved Words

Java

52abstract do ifpackage synchronizedboolean double implementsprivate thisbreak else import

C#

77abstract as basebool breakbyte case catchchar checkedclass const continue


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protected throwbyte extends instanceofpublic throwscase false intreturn transientcatch final interface

short truechar finally longstatic tryclass float nativestrictfp voidconst for newsuper volatilecontinue goto nullswitch whiledefault assert

C# doesn't haveassert boolean extendsfinal implementsinstanceof native packagestrictfp supersynchronized throwstrainsient

decimal defaultdelegate do doubleelse enumevent explicit externfalse finallyfixed float for

foreach gotoif implicit inint interfaceinternal is locklong namespacenew null objectoperator outoverride params privateprotected publicreadonly ref returnsbyte sealedshort sizeof stackallocstatic stringstruct switch this

throw truetry typeof uintulong uncheckedunsafe ushort usingvirtual voidvolatile while

Java doesn't haveas base boolchecked decimaldelegate enum eventexplicit externfixed foreach implicit

int internalis lock namespaceobject operatorout override paramsreadonly refsbyte sealed sizeofstackalloc stringstruct typeof uintulong uncheckedunsafe ushort usingvirtual

Java vs C#

Types


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Java

type:

primitive typesreference types

numeric-type:integral typesfloating-point types

integral-type:byteshortintlongchar

floating-point-type:floatdouble

reference-type:class typesinterface typesarray types

Primitive types(8)booleanbytecharshortintlongfloatdouble

C#

type:

value typesreference types

numeric-type:integral typesfloating-point typesdecimal

integral-type:sbytebyteshortushortintuintlongulongchar

floating-point-type:floatdouble

reference-type:class typesinterface typesarray typesdelegate types

Predefined types orsystem-provided types:

objectstringsbyteshortintlongbyteushortuintulongfloatdoubleboolchardecimal

NOTE: value types include simple types,enum types and struct types.


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Java vs C#

Access Modifiers

Java

public

Access not limitedprotected

Access limited to the packageor

subclass in a different package(no access modifier)

Access limited to the packageprivate

Access limited to thecontaining type

C#

public

Access not limitedprotected

Access limited to the containingclass or

types derived from the containingclass

protected internalAccess limited to this program ortypes derived from the containing

class(no access modifier)

by default it is privateinternal

Access limited to this programprivate

Access limited to the containingtype

Application Startup

Java

Only one:public static void main(String[] args){...}

C#

One of these:static void Main() {...}static void Main(string[] args)

{...}static int Main() {...}static int Main(string[] args){...}


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Array Type

Java

int [,,] array = new int [3, 4,

5];//illegalint [1,1,1] = 5;//illegalint [][][] array = new int [3][4][5]; // okint [1][1][1] = 5;

class Test{

public static voidmain(String[] args) {

int[] a1; //single-dimensional array of int

int[][] a2; // 2-

dimensional array of intint[][][] a3; // 3-

dimensional array of intint[][] j2; //

"jagged" array: array of (arrayof int)

int[][][] j3; // arrayof (array of (array of int))

}}

class Test{

public static voidmain(String[] args) {int[] a1 = new int[] {1,

2, 3};int[][] a2 = new int[][]

{{1, 2, 3}, {4, 5, 6}};int[][][] a3 = new

int[10][20][30];int[][] j2 = new int[3]

[];j2[0] = new int[] {1, 2,

3};j2[1] = new int[] {1, 2,

3, 4, 5, 6};

j2[2] = new int[] {1, 2,3, 4, 5, 6, 7, 8, 9};

}}

class Test{


C#

int [,,] array = new int [3, 4, 5]; //

creates 1 arrayint [1,1,1] = 5;int [][][] array = new int [3][4][5]; // creates 1+3+12=16 arraysint [1][1][1] = 5;

class Test{

static void Main() {int[] a1; // single-

dimensional array of intint[,] a2; // 2-dimensional

array of int

int[,,] a3; // 3-dimensionalarray of int

int[][] j2; // "jagged"array: array of (array of int)

int[][][] j3; // array of(array of (array of int))

}}

class Test{

static void Main() {int[] a1 = new int[] {1, 2,

3}; int[,] a2 = new int[,] {{1, 2,3}, {4, 5, 6}};

int[,,] a3 = new int[10, 20,30];

int[][] j2 = new int[3][];j2[0] = new int[] {1, 2, 3};j2[1] = new int[] {1, 2, 3, 4,

5, 6};j2[2] = new int[] {1, 2, 3, 4,

5, 6, 7, 8, 9};}

}

class Test{

static void Main() {int[] arr = new int[5];for (int i = 0; i

Pre-processing directivesNone

C#

{ } [ ]( ) . , : ;+ - * / % & |^ ! ~

= < > ? ++ -- &&|| >== != = += -=*= /= %= &=|= ^= = ->C# doesn't have operator >>>

Pre-processing directives#


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Out Parameters

Java

Java doesn't have out parameters.You can achieve C#'s functionalityby wrapping a primitiveto a class, or using an array tohold multiple returned values,and then call back that value viapass by reference.

class Test {

static void divide(int a, intb, int result, int remainder) {result = a / b;remainder = a % b;System.out.println(a +"/"+

b + " = "+ result +" r " + remainder);

}public static void

main(String[] args) {for (int i = 1; i < 10; i+

+)for (int j = 1; j < 10;

j++) {

int ans = 0, r = 0;divide(i, j, ans,

r);}

}}

class Test{

static void SplitPath(Stringpath, String dir, String name) {

int i = path.length();while (i > 0) {

char ch =path.charAt(i-1);

if (ch == '\\' || ch =='/' || ch == ':') break;

i--;}dir = path.substring(0, i);name = path.substring(i);

System.out.println(dir);

C#

C# provides the out keyword, whichindicates that you may pass inuninitialized variables and theywill be passed by reference.Note the calling method should markout keyword either.

class Test {

static void Divide(int a, intb, out int result, out intremainder) {

result = a / b;remainder = a % b;

}static void Main() {

for (int i = 1; i < 10; i++)

for (int j = 1; j < 10;j++) {

int ans, r;Divide(i, j, out

ans, out r);

Console.WriteLine("{0} / {1} = {2}r{3}", i, j, ans,r);

}}

}

using System;class Test{

static void SplitPath(stringpath, out string dir, out string

name) {int i = path.Length;while (i > 0) {

char ch = path[i - 1];if (ch == '\\' || ch ==

'/' || ch == ':') break;i--;

}dir = path.Substring(0, i);


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System.out.println(name);}public static void

main(String[] args) {String dir="", name ="";SplitPath("c:\\Windows\\Sys

tem\\hello.txt", dir, name);}}

prints:c:\Windows\System\hello.txt

Thanks for Peter's suggestion. He suggests touse an array as one of possible solutions in

Java to replace outparameter feature in C#.

name = path.Substring(i);}static void Main() {

string dir, name;//like aplace holder

SplitPath("c:\\Windows\\Sys

tem\\hello.txt", out dir, outname);Console.WriteLine(dir);//ca

ll backConsole.WriteLine(name);

}}prints:

c:\Windows\System\hello.txt

Override

Java

class A{

public void F() {System.out.println("A.F");

}public void G() {

System.out.println("A.G");}

}class B extends A{

public void F() {System.out.println("B.F");

}public void G() {

System.out.println("B.G");}}class Test{


B b = new B();A a = b;

C#

using System;class A

{public void F() {

Console.WriteLine("A.F");}public virtual void G() {

Console.WriteLine("A.G");}

}class B: A{

new public void F() {Console.WriteLine("B.F");

}

public override void G() {Console.WriteLine("B.G");}

}class Test{

static void Main() {B b = new B();A a = b;


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a.F();b.F();a.G();b.G();

}}

the output:B.FB.FB.GB.G

class A{

public void F() {System.out.println("A.F");

}}class B extends A{

public void F() {System.out.println("B.F");

}}class C extends B{

public void F() {System.out.println("C.F");

}}class D extends C{

public void F() {System.out.println("D.F");

}}class Test{


D d = new D();A a = new B();B b = new B();C c = d;a.F();b.F();c.F();d.F();

}}

the output:B.FB.FD.F

a.F();b.F();a.G();b.G();

}}

the output:A.FB.FB.GB.G

using System;class A{

public virtual void F() {Console.WriteLine("A.F");

}}class B: A{

public override void F() {Console.WriteLine("B.F");

}}class C: B{

new public virtual void F() {Console.WriteLine("C.F");

}}class D: C{

public override void F() {Console.WriteLine("D.F");

}}class Test{

static void Main() {D d = new D();A a = d;B b = d;C c = d;a.F();b.F();c.F();d.F();

}}the output:

B.FB.FD.FD.F


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D.F

override modifierYou cannot override to be moreprivateclass A

{public void F() {}

}class B extends A{ public void F() {}//cannot beprivate}class C extends B{

public void F() {}}You can hide B.F by controllingruntime type

override modifierclass A{

public virtual void F() {}}class B: A

{ new private void F() {} // HidesA.F within B}class C: B{

public override void F() {} //Ok, overrides A.F}

Parameter Array

Java

Java doesn't have such feature.

public class Test{

public static void main (String[]args) {

System.out.println(add (newint[] {1,2,3,4}));

}

public static int add (int[]array) {

int sum = 0;for(int i = 0; i

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