Something

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

public class ServerThread implements Runnable {
    private Socket socket = null;

    public ServerThread(Socket socket) {
        this.socket = socket;
    }

    protected DataInputStream dataIn;
    protected DataOutputStream dataOut;
    protected Thread listener;

    public synchronized void start() {
        if (listener == null) {
            try {
                dataIn=new DataInputStream
                  (new BufferedInputStream(socket.getInputStream()));
                dataOut = new DataOutputStream
                  (new BufferedOutputStream(socket.getOutputStream()));
                System.out.println("1");
                String message="has logged on\n";
                broadcast(message);

                listener = new Thread(this);
                listener.start();
            } catch (IOException ignored) {}
        }
    }

    public synchronized void stop() {
        if (listener != null) {
            try {
                if (listener != Thread.currentThread())
                    listener.interrupt();
                listener = null;
                dataOut.close();
                String msg= "logged off.\n";
                broadcast(msg);
            } catch (IOException ignored) {
            }
        }
    }

    protected static Vector handlers = new Vector();

    public void run() {
        try {
            System.out.println("2");
            handlers.addElement(this);
            while (!Thread.interrupted()) {
                String message = dataIn.readUTF();
                broadcast(message);
            }
        } catch (EOFException ignored) {
        } catch (IOException ex) {
            if (listener == Thread.currentThread())
                ex.printStackTrace();
        } finally {
            handlers.removeElement(this);
        }
        stop();
    }

    protected void broadcast(String message) {
        synchronized (handlers) {
            Enumeration enum = handlers.elements();
            while (enum.hasMoreElements()) {
                ServerThread handler = (ServerThread) enum.nextElement();
                try {
                    handler.dataOut.writeUTF(message);
                    handler.dataOut.flush();
                } catch (IOException ex) {
                    handler.stop();
                }
            }
        }
    }

    protected void broadcastNew(String message) {
        synchronized (handlers) {
            Enumeration enum = handlers.elements();
            while (enum.hasMoreElements()) {
                ServerThread handler = (ServerThread) enum.nextElement();
                try {
                    handler.dataOut.writeUTF(message);
                    handler.dataOut.flush();
                } catch (IOException ex) {
                    handler.stop();
                }
            }
        }
    }
}