Thread: Java Messenger Program?

Well here's basically what I'm trying to accomplish.
I'm trying to write a program that when run on two computers, both can send messages and the messages will appear on each one of the computers.
Basically, it's like aim.

Here's what I have so far, but this only works on the running computer, doesn't really allow other computers to connect to mine.
I'm wondering what I need to do to make this work so multiple computers can connect with each other.
Also I wasn't sure were to post this, I don't think this is much of a newbie project, but it isn't that advanced

Lesson: All About Sockets (The Java™ Tutorials > Custom Networking)

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.Iterator;
 
public class MusicServer {
ArrayList<ObjectOutputStream> clientOutputStreams;
public static void main(String[] args) {
    new MusicServer().go();
 
}
public class ClientHandler implements Runnable{
ObjectInputStream in;
Socket clientSocket;
public ClientHandler(Socket socket) {
try {
clientSocket = socket;
in = new ObjectInputStream(clientSocket.getInputStream());
} catch (Exception e) {
System.out.println(e);
}//close constructor
}
public void run(){
    Object o2 = null;
    Object o1 = null;
    try {
        while((o1 = in.readObject())!=null) {
        o2 = in.readObject();
        System.out.println("Read two objects");
        tellEveryone(o1,o2);
        }
    } catch (Exception e) {
        // TODO: handle exception
    }
}
}
public void go() {
clientOutputStreams = new ArrayList<ObjectOutputStream>();
try {
    ServerSocket serverSock = new ServerSocket(4444);
    while(true) {
        Socket clientSocket = serverSock.accept();
    ObjectOutputStream out = new ObjectOutputStream(clientSocket.getOutputStream());
    clientOutputStreams.add(out);
    Thread t = new Thread(new ClientHandler(clientSocket));
    t.start();
    System.out.println("Got a connection");
    }
} catch (Exception e) {
    e.printStackTrace();
    // TODO: handle exception
}
}
 
public void tellEveryone(ObjectOutputStream one, Object two) {
Iterator it = clientOutputStreams.iterator();
while(it.hasNext()) {
try {
ObjectOutputStream out = (ObjectOutputStream)it.next();
out.writeObject(one);
out.writeObject(two);
} catch (Exception e) {
    // TODO: handle exception
}
}
}
}

I have done this using RMI instead of socket programming.If you have problem with normal java RMI, then use the Spring
RMI samples available in to the net.

Good Luck