UDPServer

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

public class UDPServer
{
    private static HashSet<Integer> allPorts = new HashSet<Integer>();
    private GUIForServer gfs;

    public UDPServer(GUIForServer gfs)
    {
        this.gfs = gfs;
    }

    public static void main(String args[]) throws Exception
    {
        int sport = 29841;

        if (args.length < 1)
        {
            System.out.println("UDPServer is now on port: " + sport);
        }
        else
        {
            sport = Integer.valueOf(args[0]).intValue();
            System.out.println("UDPServer is now on port: " + sport);
        }

        DatagramSocket ds = null;
        ds = new DatagramSocket(sport);


        System.out.println("The server has started! \n");

        while(true)
        {
            byte[] receivedData = new byte[1024];

            DatagramPacket dp = new DatagramPacket(receivedData, receivedData.length);

            ds.receive(dp);

            String messageFromClient = (new String(dp.getData())).trim();
            System.out.println("A client has connected, the IP address and port number of the client is: " + dp.getSocketAddress());
            System.out.println("The message sent from the client was: \"" + messageFromClient + "\"");
            InetAddress ip = dp.getAddress();
            System.out.println("Client IP Address: " + ip + "\n");
            int cport = dp.getPort();
            System.out.println("Adding port number: " + cport);
            allPorts.add(cport);

            String message = messageFromClient;
            System.out.println("The message sent from the server was: " + message);

            byte[] sentData = new byte[1024];

            sentData = message.getBytes();

            for(Integer port : allPorts)
            {

                if(port != cport)
                {
                    DatagramPacket dp1 = new DatagramPacket(sentData, sentData.length, ip, port);
                    System.out.println("The message is sending...");
                    ds.send(dp1);

                }
            }
        }
    }
}