Creating a thread by implementing "Runnable" Interface

// 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

//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

//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

//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

//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

//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

//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

//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

//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

//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

//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

//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

/*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

/*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");
}
}