GROUP

 Multicast :

UDPMulticastServer:

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

public class UDPMulticastServer {

   public static void sendUDPMessage(String message,

   String ipAddress, int port) throws IOException {

      DatagramSocket socket = new DatagramSocket();

      InetAddress group = InetAddress.getByName(ipAddress);

      byte[] msg = message.getBytes();

      DatagramPacket packet = new DatagramPacket(msg, msg.length,group, port);

      socket.send(packet);

      socket.close();

   }

   public static void main(String[] args) throws IOException {

      sendUDPMessage("This is a multicast messge", "230.0.0.0",4321);

      sendUDPMessage("This is the second multicast messge","230.0.0.0", 4321);

      sendUDPMessage("This is the third multicast messge","230.0.0.0", 4321);

      sendUDPMessage("OK", "230.0.0.0", 4321);

      sendUDPMessage("This is a multicast messge", "231.0.0.0",4323);

      sendUDPMessage("This is the second multicast messge","231.0.0.0", 4323);

      sendUDPMessage("This is the third multicast messge","231.0.0.0", 4323);

      sendUDPMessage("OK", "231.0.0.0", 4323);

   }

}

UDPMulticastClient: -

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.InetAddress;

import java.net.MulticastSocket;

public class UDPMulticastClient implements Runnable {

   public static void main(String[] args) {

      Thread t=new Thread(new UDPMulticastClient());

      t.start();

   }

   public void receiveUDPMessage(String ip, int port) throws

         IOException {

      byte[] buffer=new byte[1024];

      MulticastSocket socket=new MulticastSocket(4321);

      InetAddress group=InetAddress.getByName("230.0.0.0");

      socket.joinGroup(group);

      while(true){

         System.out.println("Waiting for multicast message...");

         DatagramPacket packet=new DatagramPacket(buffer,

            buffer.length);

         socket.receive(packet);

         String msg=new String(packet.getData(),

         packet.getOffset(),packet.getLength());

         System.out.println("[Multicast UDP message received]>> "+msg);

         if("OK".equals(msg)) {

            System.out.println("No more message. Exiting : "+msg);

            break;

         }

      }

      socket.leaveGroup(group);

      socket.close();

   }

   @Override

   public void run(){

   try {

      receiveUDPMessage("230.0.0.0", 4321);

   }catch(IOException ex){

      ex.printStackTrace();

   }

}

}

UDPMulticastClient1:

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.InetAddress;

import java.net.MulticastSocket;

public class UDPMulticastClient1 implements Runnable {

   public static void main(String[] args) {

      Thread t=new Thread(new UDPMulticastClient1());

      t.start();

   }

   public void receiveUDPMessage(String ip, int port) throws

         IOException {

      byte[] buffer=new byte[1024];

      MulticastSocket socket=new MulticastSocket(4323);

      InetAddress group=InetAddress.getByName("231.0.0.0");

      socket.joinGroup(group);

      while(true){

         System.out.println("Waiting for multicast message...");

         DatagramPacket packet=new DatagramPacket(buffer,

            buffer.length);

         socket.receive(packet);

         String msg=new String(packet.getData(),

         packet.getOffset(),packet.getLength());

         System.out.println("[Multicast UDP message received]>> "+msg);

         if("OK".equals(msg)) {

            System.out.println("No more message. Exiting : "+msg);

            break;

         }

      }

      socket.leaveGroup(group);

      socket.close();

   }

   @Override

   public void run(){

   try {

      receiveUDPMessage("231.0.0.0", 4323);

   }catch(IOException ex){

      ex.printStackTrace();

   }

}

}

Output: