Java Programs Free Source Code

Exception Example(Throw and Throws )

2009-03-11T04:39:00.006-07:00

class MyExp extends Exception
{
public MyExp(String msg)
{
System.out.println(msg);
}
}

public class throws1 {
static int mtd(int a,int b) throws MyExp
{
if(b==0) throw new MyExp("Example for throw b") ;
else
if(a==0) throw new MyExp("Example for throw a") ;
return a/b;
}
public static void main(String args[])
{
try
{
System.out.print(mtd(10,0));
}
catch(Exception e)
{
System.out.println(e);
}
}
}

Exception Example

2009-03-11T04:39:00.005-07:00

Exception Example

2009-03-11T04:39:00.003-07:00

Exception Example

2009-03-11T04:39:00.001-07:00

Constructor Example

2009-03-03T22:13:00.000-08:00

public class constructor_ex {
public constructor_ex()
{
System.out.print("Constructor example");
}
public static void main(String args[])
{
constructor_ex obj=new constructor_ex();
}
}
/*constructor is a method in a class ,that has same name as that of a class.
* constructor don't have return type ,not even void.
* They automatically intialize objects with default values , when they are created.
* They are invoked using new operator .
* They can't be inherited .
* "This" and "super" can be used .
*/

Creating a thread by implementing "Runnable" Interface

2009-02-23T22:00:00.000-08:00

// Save as "thread_runnable.java"

class t1 implements Runnable
{
public void run() {
for(int i=0;i<=10;i++){
System.out.println("Values -->"+i);
}
}
}

public class thread_runnable {
public static void main(String args[])
{
t1 obj=new t1();
Thread t=new Thread(obj);
t.start();
}
}

Thread Example

2009-02-13T02:03:00.000-08:00

//Create New Thread Example - thread1.java

class ta extends Thread
{
public void run()
{
for(int i=0;i<5;i++)
{
System.out.print(i);
}
}
}
public class thread1 {
public static void main(String args[])
{
ta obj=new ta();
obj.start();
}
}

Syncronization Example

2009-02-13T02:00:00.000-08:00

//Syncronization Example - save as
//"synchornization .java"

class sa
{
static int c=10;
public synchronized int incr()
{
System.out.println("incr");
return c++;
}
public synchronized int decr()
{
System.out.println("incr1");
return c++;
}
public static synchronized int classMethod()
{
System.out.println("incr2");
//System.out.println(c++);
return c++;
}
}
public class synchornization {
public static void main(String a[])
{
sa obj=new sa();
System.out.println(obj.incr());
System.out.println(obj.decr());
System.out.println(sa.classMethod());
//System.out.println(sa.c);
//sa.classMethod();
}
}

Static Block Example

2009-02-13T01:57:00.000-08:00

//Static Block Example - save as "static_block.java"
public class static_block {
private static int static_var;
static
{
System.out.println(static_var);
System.exit(1);
}
}

Immutable class Example

2009-02-13T01:55:00.000-08:00

//Immutable class Example - save as "immutable.java"

import java.util.ArrayList;

final class immutable {
private String str=null;
public void setString(String str1)
{
str=str1;
}
public String getString()
{
ArrayList arr =new ArrayList();
arr.size();
System.out.print("------->"+arr.size());
return str;
}
public static void main(String args[])
{
immutable obj=new immutable();
obj.setString("XYZ");
ArrayList arr =new ArrayList();
arr.size();
}
}

Encapsulation Example

2009-02-13T01:53:00.000-08:00

//Encapsulation Example - save prg as "encap.java"

final class encap {
private String str=null;
public void setString(String str1)
{
str=str1;
}
public String getString()
{
return str;
}
public static void main(String args[])
{
encap obj=new encap();
obj.setString("XYZ");
System.out.print("------->"+obj.getString());
}
}

Abstract Class Example

2009-02-13T01:51:00.000-08:00

//Abstract Class Example - save prg as "abstract1 .java"

abstract class z {
abstract void mtd();
public void concrete_mtd()
{
System.out.print("Concrete Method");
}
}

class x extends z
{
public void mtd()
{
System.out.print("Abstract Method Implementation");
}
}
public class abstract1
{
public static void main(String args[])
{
x obj=new x();
obj.concrete_mtd();
}
}

Method Overriding

2009-02-13T01:46:00.000-08:00

//Method Overriding - save prog as "overrid.java" //
//To call super class methods remove the comment at super.mtd() in the prg

import java.io.*;

class oa
{
public void mtd()
{
System.out.print("super class");
}
}
class ob extends oa
{
public void mtd()
{
//super.mtd();
System.out.print("sub class");
}
}
public class overrid {
public static void main(String args[])
{
ob obj=new ob();
obj.mtd();
}
}

Multiple main methods in One Application

2009-02-13T01:42:00.000-08:00

//Multiple main methods in One Application - Save this program as "multiplemain.java"
class ma
{
public static void main(String args[])
{
System.out.print("ma");
}
}
class mb
{
public static void main(String args[])
{
System.out.print("mb");
}
}
public class multiplemain {
public static void main(String args[])
{
System.out.print("main");
}
}

Generate Random Numbers

2009-02-13T01:39:00.000-08:00

//Generate Random Numbers - Save this programe as "testrandom.java"
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Random;

public class testrandom {
public static void main(String args[])
{
HashMap hm = new HashMap();
ArrayList al= new ArrayList();
int arr[]=new int[10];
for(int i= 0 ; i< arr.length;i++)
{
arr[i]=i;
hm.put(new Random().nextInt(), i);
}
Collection coll = hm.values();
Iterator it= coll.iterator();
while(it.hasNext())
{
System.out.println("Random Values - >"+it.next());
}
}
}

palindrome Example

2009-02-13T01:37:00.000-08:00

//palindrome Example - Save this program as "palindrome.java"

class pa
{
public boolean mtd(String str)
{
int left=0 ;
int right = str.length()-1;
while ( left < right)
{
if(str.charAt(left) != str.charAt(right))
{
return false;
}
left++;
right--;
}
return true;
}
}

public class palindrome {
public static void main(String args[])
{
pa obj = new pa();
System.out.print("-->"+obj.mtd("madam"));
}
}

Reverse Of a Number Using Stack

2009-02-13T01:35:00.000-08:00

//Reverse Of a Number Using Stack
import java.util.Stack;
public class StactDemo {
public static void main(String args[])
{
Stack lifo=new Stack();
for(int i=0 ; i < 10; i++)
{
System.out.println("push operation -->"+lifo.push(i));
}
while( !lifo.empty())
{
System.out.println("pop operation -->"+lifo.pop());
}
}
}

Reverse Of a Number

2009-02-13T01:27:00.000-08:00

/*Reverse Of a Number*/
public class reverse_no {
public static void main(String args[])
{
int arr[]=new int[10];
int no=123456789;
for(int i=0;i<10;i++)
{
if(no != 0)
{
arr[i]=no%10;
no=no/10;
System.out.print(arr[i]);
}
}
}
}

Reverse Of a String

2009-02-13T01:20:00.000-08:00

/*Reverse Of a String */

class reverse
{
public void reverse123(String str)
{
String str1="";
for(int i=str.length()-1;i>=0;i--)
{
str1=str1+str.charAt(i);
}
System.out.print(str1);
}
}
public class reverse_string {
public static void main(String args[])
{
reverse obj=new reverse();
obj.reverse123("Bangalore");
}
}