• In ChatImpl, we'll need to construct an instance of this frame.  
• When we receive a message from the client in the sendMessage method, we'll need to call some method on the JFrame to update the list.

• We'll give it some simple GUI elements.  A JLabel for the title and a JList inside a JScrollPane.
• We'll need to make a DefaultListModel object, and pass that to the JList via the setModel method.  This will allow us to dynamically update the JList as we receive messages.
• We'll also need to make a method that accepts String messages and updates this JList.
• For more information on JLists and DefaultListModels, see my Java II slides on that subject.

/*
 * BulletinBoard.java
 *
 * Created on May 8, 2003, 12:32 AM
 */

package chat;

import javax.swing.DefaultListModel;

/**
 *
 * @author  default
 */
public class BulletinBoard extends javax.swing.JFrame {

    DefaultListModel model;
    
    /** Creates new form BulletinBoard */
    public BulletinBoard() {
        initComponents();
        
        // Instantiate our model, pass it to the JList.
        model = new DefaultListModel();
        lstBoard.setModel(model);
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    private void initComponents() {
        lblTitle = new javax.swing.JLabel();
        pnlButtons = new javax.swing.JPanel();
        scrBoard = new javax.swing.JScrollPane();
        lstBoard = new javax.swing.JList();
        
        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowClosing(java.awt.event.WindowEvent evt) {
                exitForm(evt);
            }
        });
        
        lblTitle.setText("jLabel1");
        getContentPane().add(lblTitle, java.awt.BorderLayout.NORTH);
        
        getContentPane().add(pnlButtons, java.awt.BorderLayout.SOUTH);
        
        scrBoard.setViewportView(lstBoard);
        
        getContentPane().add(scrBoard, java.awt.BorderLayout.CENTER);
        
        pack();
    }

    /** Exit the Application */
    private void exitForm(java.awt.event.WindowEvent evt) {
        System.exit(0);
    }

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        new BulletinBoard().show();
    }
    
    /**
     * A method to add incoming messages to the JList.
     *
     */

    public void addMessage(String message) {
        model.addElement(message);
    }
    

    // Variables declaration - do not modify
    private javax.swing.JLabel lblTitle;
    private javax.swing.JPanel pnlButtons;
    private javax.swing.JScrollPane scrBoard;
    private javax.swing.JList lstBoard;
    // End of variables declaration

}
 

package chat;

/*
 * ChatImpl.java
 *
 * Created on April 28, 2003, 11:48 PM
 */

import java.rmi.*;
import java.rmi.server.*;
import java.rmi.registry.*;
import java.net.MalformedURLException;

/** Unicast remote object implementing Chat interface.
 *
 * @author default
 * @version 1.0
 */
public class ChatImpl extends java.rmi.server.UnicastRemoteObject implements Chat {

    BulletinBoard board;
    
    /** Constructs ChatImpl object and exports it on default port.
     */
    public ChatImpl() throws RemoteException {
        super();
        // Fire up our JFrame here.
        board = new BulletinBoard();
        board.show();
    }

    /** Constructs ChatImpl object and exports it on specified port.
     * @param port The port for exporting
     */
    public ChatImpl(int port) throws RemoteException {
        super(port);
    }

    /** Register ChatImpl object with the RMI registry.
     * @param name - name identifying the service in the RMI registry
     * @param create - create local registry if necessary
     * @throw RemoteException if cannot be exported or bound to RMI registry
     * @throw MalformedURLException if name cannot be used to construct a valid URL
     * @throw IllegalArgumentException if null passed as name
     */
    public static void registerToRegistry(String name, Remote obj, boolean create) throws RemoteException, MalformedURLException{

        if (name == null) throw new IllegalArgumentException("registration name can not be null");

        try {
            Naming.rebind(name, obj);
        } catch (RemoteException ex){
            if (create) {
                Registry r = LocateRegistry.createRegistry(Registry.REGISTRY_PORT);
                r.rebind(name, obj);
            } else throw ex;
        }
    }

    /** Main method.
     */
    public static void main(String[] args) {
        System.setSecurityManager(new RMISecurityManager());

        try {
            ChatImpl obj = new ChatImpl();
            registerToRegistry("ChatImpl", obj, true);
        } catch (RemoteException ex) {
            ex.printStackTrace();
        } catch (MalformedURLException ex) {
            ex.printStackTrace();
        }
    }
    
    public void login(String user, String password) {
    }
    
    public void sendMessage(String message, String user) {
        System.out.println("Message: " + message + " User: " + user);
        // call method on JFrame to add this to our list.
        board.addMessage(message);
    }
    
}