Writing a class that receive and broadcast at the same time

[Antoine Koskoz]

Hi everybody,
I'm trying to write a class using MulticastSocket and DatagramSocket which can send messages to all clients in the same group and receive messages from them.
It's basically a chat.

The problem is it works for the first 2 messages but after no one is receiving from the others.

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class SendAndReceive
{	
    public static void main(String[] args) {
		DatagramSocket socket = null;
		String toSend = null;
		
		if (args.length != 1) {
             System.out.println("Usage: java SendAndReceive <port>");
             return;
        }
    	
    	try {
    		new Thread (new ReceiveThread()).start();    	
			socket = new DatagramSocket(Integer.parseInt(args[0]));
			InetAddress groupAdress = InetAddress.getByName("224.0.0.1");
    		
    		do {
				byte[] buf = new byte[256];
			
				Scanner sc = new Scanner (System.in);
				toSend = sc.next();
				buf = toSend.getBytes();
			
				DatagramPacket packet = new DatagramPacket(buf, buf.length, 
															groupAdress, 7654);															
										
				socket.send(packet);
			} while (toSend.trim().equalsIgnoreCase("bye"));
			socket.close();			
		} catch (IOException e) {
			e.printStackTrace();
		}
    }
}

import java.io.*;
import java.net.*;

public class ReceiveThread implements Runnable
{	
	public void run() {
		try {
			MulticastSocket socket = new MulticastSocket(7654);
			InetAddress address = InetAddress.getByName("224.0.0.1");
			socket.joinGroup(address);
			DatagramPacket packet;
	
			while (true) {
			byte[] buf = new byte[256];
			packet = new DatagramPacket(buf, buf.length);
				socket.receive(packet);

				String received = new String(packet.getData());
				System.out.println("Message reçu : " + received);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

Thanks for helping me.