Thread: Chat Program Help

I have some homework I need to finish but don't know how to do a part of it. Basically its a chat program that allows you to draw pictures to each other while you're chatting. I have everything working except I need to add a list for screen names and I need the screen names to show who typed what. Hopefully someone on here can help. Here is the code so far (5 different files but they work together). There is a server too.

Project:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import java.net.*;
 
public class Project extends JFrame implements ActionListener{
 
	JTextField tf;
	JTextArea ta;
	JScrollPane jsp;
	JButton connect, close;	
	Object in, out;
	DataObject din, dout;
	Socket s;
	ObjectOutputStream oos;
	ObjectInputStream ois;
	Listener l;
 
	DrawPanel dp;
	JPanel cp; //chat panel
	JPanel np; //name panel
 
	public Project(){
 
		setSize(500,400);
		setTitle("My Chat Program (Alpha)");
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		tf = new JTextField();
		tf.addActionListener(this);
		ta = new JTextArea();
		jsp = new JScrollPane(ta);
 
		connect = new JButton("Connect");
		connect.addActionListener(this);
		close = new JButton("Close");
		close.addActionListener(this);
 
		JPanel buttonpanel = new JPanel();
		buttonpanel.add(connect);
		buttonpanel.add(close);
 
		dp = new DrawPanel(this);
 
		cp = new JPanel();
		cp.setLayout(new BorderLayout());
		cp.add(tf,BorderLayout.NORTH);
		cp.add(jsp, BorderLayout.CENTER);
 
		np = new JPanel();
		np.setLayout(new BorderLayout());
		np.add(tf,BorderLayout.NORTH);
		np.add(jsp, BorderLayout.CENTER);
 
		JPanel wrapper = new JPanel();
		wrapper.setLayout(new GridLayout(1,0));
		wrapper.add(cp);
		wrapper.add(dp);
		wrapper.add(np);
 
		getContentPane().add(wrapper, BorderLayout.CENTER);
		getContentPane().add(buttonpanel, BorderLayout.SOUTH);
 
 
		setVisible(true);
	}
 
	public void actionPerformed(ActionEvent ae){
		Object obj = ae.getSource();
 
		if(obj == connect){
			try{
				s = new Socket("localhost", 8189);
				oos = new ObjectOutputStream(s.getOutputStream());
 
				dout = new DataObject();
				l = new Listener(s);
				l.start();
				connect.setEnabled(false);
 
			}catch(Exception e){
 
				System.out.println(e.getMessage());
			}
		}else{
			String temp = tf.getText();
			tf.setText("");
			dout.setMessage(temp);
			try{	
				oos.writeObject(dout);
				oos.reset();
			}catch(Exception e){
 
				System.out.println(e.getMessage());
			}
			//ta.append(temp + "\n");
		}
	}
 
	class Listener extends Thread{
 
		Socket s;
 
		public Listener(Socket s){
			this.s = s;
		}
		public void run(){
		   try{
		       ois = new ObjectInputStream(s.getInputStream());
 
		       while(true){
		          in = ois.readObject();
 
			  if(in instanceof DataObject){
			     din = (DataObject)in;
			     String text = din.getMessage() + "\n";
			     ta.append(text);
			     SwingUtilities.invokeLater(new Runnable() {
        		          public void run() {
              			      ta.setCaretPosition(ta.getText().length());
        			  }
      			     });
 
			   }else if(in instanceof LineObject){
 
				LineObject lo = (LineObject)in;
				dp.backg.drawLine(lo.getStartX(), lo.getStartY(), 
					lo.getEndX(), lo.getEndY());
				dp.record(lo.getEndX(), lo.getEndY());
      				dp.repaint();
 
				//grab the drawpanel
				//draw the current line	
 
			   }
		      }//end while
		   }catch(Exception e){
			System.out.println(e.getMessage());
		   }	
		}
 
	}
 
 
	public static void main(String[] args){
 
		new Project();
 
	}
}

Server:

import java.io.*;
import java.net.*;
import java.util.*;
 
public class Server{
 
	public static void main(String[] args) throws Exception{
		ArrayList handlerList = new ArrayList();
		ServerSocket ss = new ServerSocket(8189);
		while(true){
			Socket s = ss.accept();
			Handler h = new Handler(s, handlerList);
			h.start();
			handlerList.add(h);
		}
	}
}
 
class Handler extends Thread{
 
	Socket s;
	//DataObject d;
	Object d;	
	ArrayList handlers;
	ObjectInputStream ois;
	ObjectOutputStream oos;
 
	public Handler(Socket s, ArrayList al){
 
		this.s = s;
		handlers = al;
	}
 
	public void broadcast(Object in){
		Iterator itr = handlers.iterator();
 
    		//use hasNext() and next() methods to iterate through the elements
    		//System.out.println("Iterating through ArrayList elements...");
    		while(itr.hasNext()){
      			Handler current = (Handler)itr.next();
			current.writeObject(in);
 
		}
 
	}
	public void writeObject(Object d){
		try{
			oos.writeObject(d);
			oos.reset();
		}catch(Exception e){
			System.out.println(e.getMessage());
		}
	}
 
	public void run(){
		try{
			ois = new ObjectInputStream(s.getInputStream());
			oos = new ObjectOutputStream(s.getOutputStream());
			while(true){
				d = ois.readObject();
				if(d == null){
					break;
				}	
				//System.out.println(d.getMessage());
 
				//d.setMessage("This is the changed message.");
				//System.out.println(d.getMessage());		
 
				broadcast(d);
				//oos.writeObject(d);
				//oos.reset();
			}
 
 
			ois.close();
			oos.close();
			s.close();
		}catch(IOException ioe){
			System.out.println(ioe.getMessage());
		}catch(ClassNotFoundException cnfe){
			System.out.println("Class DataObject not found.");
		}
	}
}
/*
ArrayList arrayList = new ArrayList();
 
    //Add elements to Arraylist
    arrayList.add("1");
    arrayList.add("2");
    arrayList.add("3");
    arrayList.add("4");
    arrayList.add("5");
 
    Iterator itr = arrayList.iterator();
 
    while(itr.hasNext())
      System.out.println(itr.next());
*/

Data Object:
(For Server and Project)

import java.io.*;
 
public class DataObject implements Serializable{
 
	String message;
 
	public DataObject(){}
 
	public void setMessage(String m){
 
		message = m;
	}
	public String getMessage(){
 
		return message;
	}
}

DrawPanel:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class DrawPanel extends Panel
	implements MouseListener, MouseMotionListener {
 
	int lastx, lasty;
   	int width, height;
   	Image backbuffer;
   	Graphics backg;
		LineObject lo;
		Project parent;
 
   	public DrawPanel() {
      	width = 400;
      	height = 400;
			Dimension d = new Dimension(width, height);
      	setPreferredSize(d);	
			addMouseListener(this);
			addMouseMotionListener( this );
   	}
	public DrawPanel(Project p){
		this();
		parent = p;
 
	}
	public void record(int x, int y){
		lastx = x;
		lasty = y;
	}
   	public void createBackBuffer(){
 
      		backbuffer = createImage( width, height );
      		backg = backbuffer.getGraphics();
      		backg.setColor( Color.black );
      		backg.fillRect( 0, 0, width, height );
      		backg.setColor( Color.white );
   	}
 
	public void mouseEntered( MouseEvent e ) { 
		record(e.getX(), e.getY());
	}
	public void mouseExited( MouseEvent e ) { }
	public void mousePressed( MouseEvent e ) {
		record(e.getX(), e.getY());
	}
	public void mouseClicked( MouseEvent e ) { 
		if(e.getModifiers() == InputEvent.BUTTON3_MASK){
			backg.setColor( Color.black );
      			backg.fillRect( 0, 0, width, height );
      			backg.setColor( Color.white );
			repaint();
		}
	}
	public void mouseReleased( MouseEvent e ) { }
 
 
 
   	public void mouseMoved( MouseEvent e ) { }
   	public void mouseDragged( MouseEvent e ) {
      		int x = e.getX();
      		int y = e.getY();
 
		lo = new LineObject(lastx, lasty, x, y);
 
		//backg.drawLine(lo.getStartX(), lo.getStartY(), 
		//			lo.getEndX(), lo.getEndY());
 
 
		//record(x, y);
      		//repaint();
      		//e.consume();
 
		try{	
			parent.oos.writeObject(lo);
			parent.oos.reset();
		}catch(Exception ex){
			System.out.println(ex.getMessage());
		}
   	}
 
   	public void update( Graphics g ) {
		if(backg == null){	
			createBackBuffer();
		}
      		g.drawImage( backbuffer, 0, 0, this );
   	}
 
   	public void paint( Graphics g ) {
      		update( g );
   	}
 
	public static void main(String[] args){
		DrawPanel dp = new DrawPanel();	
		dp.setSize(400,400);
 
		Frame f = new Frame();
		f.setSize(400,400);
		f.setTitle("Drawing");
		f.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent we){
 
				System.exit(0);
			}
		});
 
		f.add(dp, BorderLayout.CENTER);
		f.pack();
		f.setVisible(true);
	}
}

Line Object:
(For Draw Panel and Project)

import java.io.*;
 
public class LineObject implements Serializable{
 
	int startx, starty, endx, endy;
 
	public LineObject(int sx, int sy, int ex, int ey){ 
 
		startx = sx;
		starty = sy;
		endx = ex;
		endy = ey;
	}
	public void setLine(int sx, int sy, int ex, int ey){ 
 
		startx = sx;
		starty = sy;
		endx = ex;
		endy = ey;
	}
 
	public int getStartX(){
		return startx;
	}
	public int getStartY(){
		return starty;
	}
	public int getEndX(){
		return endx;
	}
	public int getEndY(){
		return endy;
	}
}