Problem updating JTree via RMI

Question

I'm programming an Instant Messenger application in Java using RMI extensively. Much like most IM applications, my IM clients display a "buddy list" window upon successful authentication with the server. I have reached a huge stumbling block at this point. My Buddylist JFrame contains a JTree that is used to display the status of the user's buddies (i.e. online, offline). I am able to populate the JTree without any problems BEFORE the JFrame is displayed by using the DefaultTreeModel's insertNodeInto() method. But the problem I'm having is that, once the Buddylist is displayed to the user, I can't successfully update the JTree to reflect changing user status. For example, let's say a user with the screename "qwerty" logs in to the server. Now "qwerty" sees his Buddylist pop up on screen. His Buddylist contains 1 user (for simplicity's sake) with screename "foo". "foo" is currently not logged into the system so "foo" is shown in the Buddylist as a child of node Offline. But right now, let's say that "foo" logs into the system. "qwerty's" Buddylist should be updated to reflect the fact that "foo" just signed in by removing "foo" as a child node of Offline and adding a new node to Online called "foo".
I currently have this functionality implemented as an RMI callback method on the server side. When "foo" logs in, the server calls the method fireBuddyLoggedOnEvent() with "foo" as the argument. Because "qwerty" is already logged in, and both users are each other's buddy, the statement
     c.getCallback().buddySignedOn(screenname);
will be executed on the client side. Unfortunately, even though this code is successfully executed remotely, "qwerty's" Buddylist's JTree does not update to show that "foo" is now online. My only suspicion is that this is due to the fact that the Buddylist is already visible and this somehow affects its ability to be updated (remember that I have no problem populating the tree BEFORE it's visible). However, I've weeded out this possibility by creating a test frame in which its JTree is successfully updated, but in response to an ActionEvent in response to a button click. Of course, this test case was not an RMI application and does not come with the complexities of RMI. Please help me resolve this issue as it's preventing me from proceeding with my project.
~BTW, sorry for the poor code formatting. I added all the code in wordpad and pasted it in here, which stripped the formatting.
* Frame that allows the user to enter information to
* be used to login to the server.
public class LoginFrame extends JFrame {
     signonButton.addActionListener(new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent e) {
               if (!screenameTextField.getText().equals("") &&
               !passwordTextField.getPassword().equals("")) {
                    try {
                         serverInter = (ServerInter) Naming.lookup(serverName);
                         String username = screenameTextField.getText();
                         String password = String.valueOf(passwordTextField.getPassword());
                         int connectionID = serverInter.connect(username, password);
                         System.out.println("authenticate successful");
                         dispose();
                         Buddylist buddyList = new Buddylist(username, connectionID);
                         // Registers the buddylist with the server so that
                         // the server can remotely call methods on the
                         // Buddylist.
                         serverInter.registerCallback(buddyList, connectionID);
                         return;
                         } catch (Exception e1) {
                              JOptionPane.showMessageDialog(LoginFrame.this, e1.getMessage(),
                                        "Connection Error", JOptionPane.ERROR_MESSAGE);
                              passwordTextField.setText("");
                              signonButton.setEnabled(false);
                              e1.printStackTrace();
     public static void main(String[] args) {
          new LoginFrame();
public class Buddylist extends JFrame implements BuddylistInter {
     public Buddylist(String username, int connectionID) {
          try {
               serverInter = (ServerInter) Naming.lookup(serverName);
               this.username = username;
               this.connectionID = connectionID;
               this.setTitle(username + "'s BuddyList");
               initialize();
               } catch (Exception e) {
                    e.printStackTrace();
     * Method of interest. Note that this method uses a DynamicTree
     * object as included in the Sun tutorial on JTree's
     * (located at http://www.iam.ubc.ca/guides/javatut99/uiswing/components/tree.html#dynamic).
     * Don't worry too much about where the node is getting added
     * but rather, that i wish to verify that an arbitrary node
     * can successfully be inserted into the tree during this
     * remote method call
     public void buddySignedOn(String screenname) throws RemoteException {
          // should add screename at some location in the tree
          // but doesn't!
          treePanel.addObject(screename);
* Oversimplified interface for the Buddylist that is intended
* to be used to allow callbacks to the clientside.
public interface BuddylistInter extends Remote {
     public void buddySignedOn(String screenname) throws RemoteException;
* Another oversimplified interface that is to be
* implemented by the server so that the client can
* call remote server methods.
public interface ServerInter extends java.rmi.Remote {
     // "Registers" the given Buddylist with this server to allow
     // remote callbacks on the Buddylist.
     public void registerCallback(Buddylist buddylist, int connectionID)
                         throws RemoteException;
public class Server extends UnicastRemoteObject implements ServerInter {
     private Vector loggedInUsers = new Vector();
     // Note that this method assumes that a Connection object
     // representing the Buddylist with connectionID was added
     // to the loggedInUsers list during authentication.
     public void registerCallback(Buddylist buddylist, int connectionID) throws RemoteException {          
          int index = loggedInUsers.indexOf(new Connection(connectionID));
          Connection c = (Connection) loggedInUsers.get(index);
          c.setCallback(buddylist);
     // Method that's called whenever a client successfully
     // connects to this server object.
     // screename is the name of the user that successfully
     // logged in.
     private void fireBuddyLoggedOnEvent(String screenname) {
          // Examines each logged in client to determine whether
          // or not that client should be notified of screename's
          // newly logged in status.
          for (int i = 0; i < loggedInUsers.size(); i++) {
               Connection c = (Connection) loggedInUsers.get(i);
               if (database1.areBuddies(screenname, c.getUsername())) {
                    try {
                         // getCallback() returns a reference to
                         // the Buddylist that was registered
                         // with this server. At this point,
                         // the server attempts to notify the
                         // client that one of his "buddies" has
                         // just logged into the server.
                         c.getCallback().buddySignedOn(screenname);
                    } catch (RemoteException e) {
                         e.printStackTrace();
}

Answer 1

Ok, I deleted all .class files, recomplied, and rmic'd, and I still get the IllegalArgumentException. So I've decided to just post all the code here because I don't want to make an assumption that all the code is correct. Thanks for helping me out with this very stressful problem.
* Created on Nov 13, 2006
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.SwingUtilities;
import javax.swing.tree.DefaultMutableTreeNode;
public class Buddylist extends JFrame implements BuddylistInter {
     private String serverName = "//Broom:" + "5001" + "/IMServer";
     private DynamicTree treePanel = null;
     private String onlineString = "Online";
     private String offlineString = "Offline";
     private DefaultMutableTreeNode onlineNode = null;
     private DefaultMutableTreeNode offlineNode = null;
     private ImageUpdater imageUpdater = null;
     private javax.swing.JPanel jContentPane = null;
     private ServerInter serverInter = null;
     private String username = null;
     // A connectionID of -1 indicates that this Buddylist
     // has not yet received a valid id from the server.
     private int connectionID = -1;
     private JMenuBar jJMenuBar = null;
     private JMenu jMenu = null;
     private JMenu jMenu1 = null;
     private JMenu jMenu2 = null;
     private JPanel imagePanel = null;
     private JSeparator jSeparator1 = null;
     public Buddylist(String username, int connectionID) {
         try {
               serverInter = (ServerInter) Naming.lookup(serverName);
               this.username = username;
               this.connectionID = connectionID;
               this.setTitle(username + "'s BuddyList");
               imageUpdater = new ImageChooser(this);
               initialize();
                * This statement is causing an IllegalArgumentException
                * to be thrown! I've tried inserting it at the beginning
                * of the constructor and that doesn't help.
               UnicastRemoteObject.exportObject(this);
          } catch (MalformedURLException e) {
               e.printStackTrace();
          } catch (RemoteException e) {
               e.printStackTrace();
          } catch (NotBoundException e) {
               e.printStackTrace();
      * This method initializes this
      * @return void
     private void initialize() {
          this.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
          this.setJMenuBar(getJJMenuBar());
          this.setPreferredSize(new java.awt.Dimension(196,466));
          this.setMinimumSize(new java.awt.Dimension(150,439));
          this.setSize(196, 466);
          this.setContentPane(getJContentPane());
          this.setLocationRelativeTo(null);
          this.setVisible(true);
      * This method initializes jContentPane
      * @return javax.swing.JPanel
     private javax.swing.JPanel getJContentPane() {
          if(jContentPane == null) {
               jContentPane = new javax.swing.JPanel();
               jContentPane.setLayout(null);
               jContentPane.add(getImagePanel(), null);
               jContentPane.add(getJSeparator1(), null);
               jContentPane.add(getTreePanel(), null);
          return jContentPane;
     private DynamicTree getTreePanel() {
          if (treePanel == null) {
               treePanel = new DynamicTree();
               onlineNode = treePanel.addObject(null, onlineString);
               offlineNode = treePanel.addObject(null, offlineString);
               treePanel.setBounds(6, 138, 177, 196);
               populateTree();
               return treePanel;
          return null;
     private void populateTree() {
          try {
               String [] buddies = serverInter.getBuddyList(this.username);
               for (int i = 0; i < buddies.length; i++) {
                    try {
                         if (serverInter.isBuddyOnline(buddies)) {
                              treePanel.addObject(onlineNode, buddies[i]);
                         else {
                              treePanel.addObject(offlineNode, buddies[i]);
                    } catch (RemoteException e1) {
                         e1.printStackTrace();
          } catch (RemoteException e) {
               e.printStackTrace();
     * This method initializes jJMenuBar     
     * @return javax.swing.JMenuBar     
     private JMenuBar getJJMenuBar() {
          if (jJMenuBar == null) {
               jJMenuBar = new JMenuBar();
               jJMenuBar.add(getJMenu());
               jJMenuBar.add(getJMenu1());
               jJMenuBar.add(getJMenu2());
          return jJMenuBar;
     * This method initializes jMenu     
     * @return javax.swing.JMenu     
     private JMenu getJMenu() {
          if (jMenu == null) {
               jMenu = new JMenu();
               jMenu.setText("My IM");
          return jMenu;
     * This method initializes jMenu1     
     * @return javax.swing.JMenu     
     private JMenu getJMenu1() {
          if (jMenu1 == null) {
               jMenu1 = new JMenu();
               jMenu1.setText("People");
          return jMenu1;
     * This method initializes jMenu2     
     * @return javax.swing.JMenu     
     private JMenu getJMenu2() {
          if (jMenu2 == null) {
               jMenu2 = new JMenu();
               jMenu2.setText("Help");
          return jMenu2;
     * This method initializes imagePanel     
     * @return javax.swing.JPanel     
     private JPanel getImagePanel() {
          if (imagePanel == null) {
               imagePanel = new JPanel();
               imagePanel.setBounds(6, 2, 176, 125);
               try {
                    BufferedImage bi =
                         ImageIO.read(
                                   getClass().getClassLoader().getResourceAsStream("images/cute_dog.jpg"));
                    Image scaled = bi.getScaledInstance(
                              imagePanel.getWidth(), imagePanel.getHeight(), BufferedImage.SCALE_FAST);
                    final JLabel imageLabel = new JLabel(new ImageIcon(scaled));
                    imageLabel.setToolTipText("Double click to change image");
                    imagePanel.add(imageLabel, imageLabel.getName());
                    imageLabel.addMouseListener(new java.awt.event.MouseAdapter() {
                         public void mouseClicked(java.awt.event.MouseEvent e) {
                              if (e.getClickCount() == 2) {
                                   Image selected = imageUpdater.getSelectedImage();
                                   if (selected != null) {
                                        BufferedImage bi = (BufferedImage) selected;
                                        Image scaled = bi.getScaledInstance(
                                                  imageLabel.getWidth(), imageLabel.getHeight(), BufferedImage.SCALE_DEFAULT);
                                        imageLabel.setIcon(new ImageIcon(scaled));
               } catch (IOException e) {
                    e.printStackTrace();
          return imagePanel;
     * This method initializes jSeparator1     
     * @return javax.swing.JSeparator     
     private JSeparator getJSeparator1() {
          if (jSeparator1 == null) {
               jSeparator1 = new JSeparator();
               jSeparator1.setBounds(6, 132, 176, 1);
          return jSeparator1;
     public void buddySignedOn(String screenname) throws RemoteException {
          final String temp = screenname;
          Runnable addBuddy = new Runnable() {
               public void run() {
                    treePanel.addObject(onlineNode, temp);
          SwingUtilities.invokeLater(addBuddy);
     public void buddySignedOff(String screenname) throws RemoteException {
          // TODO Auto-generated method stub
     public boolean equals(Object o) {
          Buddylist buddylist = (Buddylist) o;
          return connectionID == buddylist.connectionID;
     public int hashCode() {
          return connectionID;
} // @jve:decl-index=0:visual-constraint="10,11"
* Created on Nov 4, 2006
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface BuddylistInter extends Remote {
     public void buddySignedOn(String screenname) throws RemoteException;
     public void buddySignedOff(String screenname) throws RemoteException;
* Created on Oct 14, 2006
* Models a single endpoint of a connection between machines.
* @author Josh Feldman
public class Connection {
     private String username;
     private final int connectionID;
     private Buddylist callback = null;
     public Connection(String username, int connectionID) {
          this.username = username;
          this.connectionID = connectionID;
     public Connection(int connectionID) {
          this.connectionID = connectionID;
     public String getUsername() {
          return username;
     public int getConnectionID() {
          return connectionID;
     public void setCallback(Buddylist buddylist) {
          this.callback = buddylist;
     public Buddylist getCallback() {
          return callback;
     public boolean equals(Object o) {     
          Connection otherConnection = (Connection) o;
          if (otherConnection.getConnectionID() == this.connectionID) {
               return true;
          else {
               return false;
     public int hashCode() {
          return connectionID;
* Created on Nov 4, 2006
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.Serializable;
import java.util.Properties;
public class Database implements Serializable{
     private final String regex = ";";
     private Properties db = null;
     private String dbPath = "buddies.txt";
     public Database() throws IOException {
          db = new Properties();
          File buddiesFile = new File(dbPath);
          if (!buddiesFile.canRead()) {
               throw new IOException("Can't read database!");
          try {
               FileInputStream fis = new FileInputStream(buddiesFile);
               db.load(fis);
               System.out.println("database loaded from file");
          } catch (IOException e) {
               e.printStackTrace();
               System.err.println("Can't load the database! Exiting program...");
               System.exit(0);
      * called when a user adds/deletes a user from the buddylist
     public void changeBuddyList() {
          //TODO
     public boolean doesUserExist(String username) {
          System.out.println(db.getProperty(username));
          return db.getProperty(username) != null;
     public String getPassword(String username) {
          String temp = db.getProperty(username);
          String [] split = temp.split(regex);
          if (split.length == 2)
               return split[0];
          else {
               return null;
     public String getBuddies(String username) {
          String temp = db.getProperty(username);
          if (temp == null)
               return null;
          String [] split = temp.split(regex);
          if (split.length != 2)
               return null;
          else {
               return split[1];
      * Determines whether screename1 is a buddy of screename2
      * @return
     public boolean areBuddies(String screename1, String screename2) {
          String [] buddies = getUserBuddies(screename2);
          if (buddies == null) {
               return false;
          else {
               for (int i = 0; i < buddies.length; i++) {
                    if (buddies.equals(screename1)) {
                         return true;
          return false;
     public String [] getUserBuddies(String username) {
          System.out.println("in db getUserBuddies: username = " + username);
          String temp = db.getProperty(username);
          if (temp == null)
               return null;
          String [] split = temp.split(regex);
          if (split.length != 2)
               return null;
          else {
               return split[1].split(",");
import java.awt.GridLayout;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.event.TreeModelEvent;
import javax.swing.event.TreeModelListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.MutableTreeNode;
import javax.swing.tree.TreePath;
import javax.swing.tree.TreeSelectionModel;
// Note that this is not my code but rather code taken
// from java Sun tutorial
public class DynamicTree extends JPanel {
    protected DefaultMutableTreeNode rootNode;
    protected DefaultTreeModel treeModel;
    protected JTree tree;
    public DynamicTree() {
        rootNode = new DefaultMutableTreeNode("Root Node");
        treeModel = new DefaultTreeModel(rootNode);
        treeModel.addTreeModelListener(new MyTreeModelListener());
        tree = new JTree(treeModel);
        tree.setRootVisible(false);
        tree.setEditable(false);
        tree.getSelectionModel().setSelectionMode
                (TreeSelectionModel.SINGLE_TREE_SELECTION);
        tree.setShowsRootHandles(false);
        JScrollPane scrollPane = new JScrollPane(tree);
        setLayout(new GridLayout(1,0));
        add(scrollPane);
    /** Remove all nodes except the root node. */
    public void clear() {
        rootNode.removeAllChildren();
        treeModel.reload();
    /** Remove the currently selected node. */
    public void removeCurrentNode() {
        TreePath currentSelection = tree.getSelectionPath();
        if (currentSelection != null) {
            DefaultMutableTreeNode currentNode = (DefaultMutableTreeNode)
                         (currentSelection.getLastPathComponent());
            MutableTreeNode parent = (MutableTreeNode)(currentNode.getParent());
            if (parent != null) {
                treeModel.removeNodeFromParent(currentNode);
                return;
    public void removeObject(DefaultMutableTreeNode child) {
         treeModel.removeNodeFromParent(child);
//         treeModel.reload();
    /** Add child to the currently selected node. */
    public DefaultMutableTreeNode addObject(Object child) {
        DefaultMutableTreeNode parentNode = null;
        TreePath parentPath = tree.getSelectionPath();
        if (parentPath == null) {
            parentNode = rootNode;
        } else {
            parentNode = (DefaultMutableTreeNode)
                         (parentPath.getLastPathComponent());
        return addObject(parentNode, child, true);
    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
                                            Object child) {
        return addObject(parent, child, false);
    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
                                            Object child,
                                            boolean shouldBeVisible) {
        DefaultMutableTreeNode childNode =
                new DefaultMutableTreeNode(child);
        if (parent == null) {
            parent = rootNode;
        treeModel.insertNodeInto(childNode, parent,
                                 parent.getChildCount());
        // Make sure the user can see the lovely new node.
        if (shouldBeVisible) {
            tree.scrollPathToVisible(new TreePath(childNode.getPath()));
        return childNode;
    class MyTreeModelListener implements TreeModelListener {
        public void treeNodesChanged(TreeModelEvent e) {
            DefaultMutableTreeNode node;
            node = (DefaultMutableTreeNode)
                     (e.getTreePath().getLastPathComponent());
             * If the event lists children, then the changed
             * node is the child of the node we've already
             * gotten.  Otherwise, the changed node and the
             * specified node are the same.
            try {
                int index = e.getChildIndices()[0];
                node = (DefaultMutableTreeNode)
                       (node.getChildAt(index));
            } catch (NullPointerException exc) {}
            System.out.println("The user has finished editing the node.");
            System.out.println("New value: " + node.getUserObject());
        public void treeNodesInserted(TreeModelEvent e) {
        public void treeNodesRemoved(TreeModelEvent e) {
        public void treeStructureChanged(TreeModelEvent e) {
    public DefaultTreeModel getModel() {
         return treeModel;
* Created on Sep 24, 2006
import java.awt.Frame;
import java.awt.Image;
import javax.swing.JComponent;
* Generic Dialog for allowing a user to browse
* his filesystem for an image file. Dialog
* displays a preview of the image (if it is in fact
* displayable).
* @author Josh Feldman
public class ImageChooser extends JComponent implements ImageUpdater{
     private Frame parent = null;
     public ImageChooser(Frame parent) {
          super();
          this.parent = parent;
     public Image getSelectedImage() {
          ImageChooserDialog dialog = new ImageChooserDialog(parent);
          if (dialog.showDialog() == ImageChooserDialog.OK_OPTION) {
               return dialog.getSelectedImage();
          return null;
}  //  @jve:decl-index=0:visual-constraint="10,10"
* Created on Sep 24, 2006
import java.awt.Frame;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JDialog;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
* Class that displays a dialog that allows a user
* to browse his/her filesystem for an image file
* for selection.
* @author Josh Feldman
public class ImageChooserDialog extends JDialog {
     private Frame parent = null;
     private JFileChooser fileChooser = new JFileChooser();
     private int option;
     public final static int OK_OPTION = 1;
     public final static int CANCEL_OPTION = 2;
     private Image selectedImage = null;
     private javax.swing.JPanel jContentPane = null;
     private JPanel previewPanel = null;
     private JLabel jLabel = null;
     private JTextField filenameTextField = null;
     private JButton browseButton = null;
     private JButton cancelButton = null;
     private JButton okButton = null;
     private JLabel previewLabel = null;
      * This is the default constructor
     public ImageChooserDialog(Frame parent) {
          super();
          this.parent = parent;
          this.setTitle("Select Image");
          initialize();
     public ImageChooserDialog(Frame parent, String title) {
          super();
          this.parent = parent;
          this.setTitle(title);
          initialize();
      * This method initializes this
      * @return void
     private void initialize() {
          this.setModal(true);
          this.setSize(377, 246);
          this.setContentPane(getJContentPane());
          this.setVisible(false);
          this.setLocationRelativeTo(parent);
          this.addWindowListener(new java.awt.event.WindowAdapter() {
               public void windowClosing(java.awt.event.WindowEvent e) {
                    selectedImage = null;
                    option = CANCEL_OPTION;
      * This method initializes jContentPane
      * @return javax.swing.JPanel
     private javax.swing.JPanel getJContentPane() {
          if(jContentPane == null) {
               jLabel = new JLabel();
               jContentPane = new javax.swing.JPanel();
               jContentPane.setLayout(null);
               jLabel.setBounds(87, 192, 58, 10);
               jLabel.setText("Preview");
               jContentPane.add(getPreviewPanel(), null);
               jContentPane.add(jLabel, null);
               jContentPane.add(getFilenameTextField(), null);
               jContentPane.add(getBrowseButton(), null);
               jContentPane.add(getCancelButton(), null);
               jContentPane.add(getOkButton(), null);
          return jContentPane;
      * This method initializes previewPanel     
      * @return javax.swing.JPanel     
     private JPanel getPreviewPanel() {
          if (previewPanel == null) {
               previewPanel = new JPanel();
               previewLabel = new JLabel();
               previewPanel.setLayout(null);
               previewPanel.setLocation(25, 62);
               previewPanel.setSize(172, 125);
               previewPanel.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.LOWERED));
               previewLabel.setText("");
               previewLabel.setLocation(2, 2);
               previewLabel.setSize(172, 125);
               previewPanel.add(previewLabel, null);
          return previewPanel;
      * This method initializes jTextField     
      * @return javax.swing.JTextField
     private JTextField getFilenameTextField() {
          if (filenameTextField == null) {
               filenameTextField = new JTextField();
               filenameTextField.setBounds(26, 17, 212, 23);
               filenameTextField.setEditable(false);
          return filenameTextField;
      * This method initializes jButton     
      * @return javax.swing.JButton     
     private JButton getBrowseButton() {
          if (browseButton == null) {
               browseButton = new JButton();
               browseButton.setBounds(254, 18, 102, 21);
               browseButton.setText("Browse");
               browseButton.addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) { 
                         ImageFilter imageFilter = new ImageFilter();
                         fileChooser.setFileFilter(imageFilter);
                         int value = fileChooser.showOpenDialog(ImageChooserDialog.this);
                         if (value == JFileChooser.APPROVE_OPTION) {
                              File selected = fileChooser.getSelectedFile();
                              if (selected.canRead()) {
                                   try {
                                        BufferedImage bi = ImageIO.read(selected);
                                        selectedImage = bi;
                                        Image scaled = bi.getScaledInstance(
                                                  previewPanel.getWidth(), previewPanel.getHeight(), BufferedImage.SCALE_FAST);
                                        ImageIcon imageIcon = new ImageIcon(scaled);
                                        previewLabel.setIcon(imageIcon);
                                        filenameTextField.setText(selected.getAbsolutePath());
                                   } catch (IOException e1) {
                                        previewLabel.setText("Preview unavailable...");
                                        selectedImage = null;
                                        e1.printStackTrace();
          return browseButton;
      * This method initializes jButton1     
      * @return javax.swing.JButton     
     private JButton getCancelButton() {
          if (cancelButton == null) {
               cancelButton = new JButton();
               cancelButton.setBounds(254, 122, 100, 24);
               cancelButton.setText("Cancel");
               cancelButton.addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                         selectedImage = null;
                         option = CANCEL_OPTION;
                         ImageChooserDialog.this.dispose();
          return cancelButton;
      * This method initializes jButton2     
      * @return javax.swing.JButton     
     private JButton getOkButton() {
          if (okButton == null) {
               okButton = new JButton();
               okButton.setBounds(256, 159, 97, 24);
               okButton.setText("OK");
               okButton.addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                         option = OK_OPTION;
                         ImageChooserDialog.this.dispose();
          return okButton;
      * Displays this chooser dialog.
      * @return - The user selected option
      *                (i.e. OK_OPTION, CANCEL_OPTION)
     public int showDialog() {
          this.setVisible(true);
          return option;
      * Returns the image chosen by the user.
      * @return
     public Image getSelectedImage() {
          return selectedImage;
import java.io.File;
import javax.swing.filechooser.FileFilter;
public class ImageFilter extends FileFilter {
    //Accept all directories and all gif, jpg, tiff, or png files.
    public boolean accept(File f) {
        if (f.isDirectory()) {
            return true;
        String extension = Utils.getExtension(f);
        if (extension != null) {
            if (extension.equals(Utils.tiff) ||
                extension.equals(Utils.tif) ||
                extension.equals(Utils.gif) ||
                extension.equals(Utils.jpeg) ||
                extension.equals(Utils.jpg) ||
                extension.equals(Utils.png)) {
                    return true;
            } else {
                return false;
        return false;
    //The description of this filter
    public String getDescription() {
        return "Just Images";
* Created on Sep 24, 2006
import java.awt.Image;
* Contract that specifies how a class can update
* the view in its graphical display.
* @author Josh Feldman
public interface ImageUpdater {
     public Image getSelectedImage();
* Created on Nov 4, 2006
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.rmi.Naming;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
public class LoginFrame extends JFrame {
     private String serverName = "//Broom:5001/IMServer";
     private ServerInter serverInter = null;
     // The icon to be used when this frame is minimized
     private Image icon;
     // The main image to be displayed on this frame
     private Image robotImage;
     private javax.swing.JPanel jContentPane = null;
     private JPanel imagePanel = null;
     private JLabel screenameLabel = null;
     private JTextField screenameTextField = null;
     private JPanel jPanel1 = null;
     private JLabel passwordLabel = null;
     private JPasswordField passwordTextField = null;
     private JButton signonButton = null;
     private JButton helpButton = null;
      * This is the default constructor
     public LoginFrame() {
          initialize();
      * This method initializes this
      * @return void
     private void initialize() {
          this.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
          this.setResizable(false);
          this.setSize(210, 368);
          this.setContentPane(getJContentPane());
          this.setTitle("Sign On");
          try {
               this.setIconImage(ImageIO.read(new File("images/robby3.jpg")));
          } catch (IOException e) {
               e.printStackTrace();
          this.setLocationRelativeTo(null);
          this.setVisible(true);
      * This method initializes jPanel     
      * @return javax.swing.JPanel     
     private JPanel getImagePanel() {
          if (imagePanel == null) {
               imagePanel = new JPanel();
               imagePanel.setBounds(7, 7, 190, 159);
               imagePanel.setBorder(javax.swing.BorderFactory.createLineBorder(java.awt.Color.gray,0));
               try {
                    BufferedImage bi =
                         ImageIO.read(
                                   getClass().getClassLoader().getResourceAsStream("images/robby_big.bmp"));
                    Image scaled = bi.getScaledInstance(190, 169, BufferedImage.SCALE_FAST);
                    JLabel robotLabel = new JLabel(
                              new ImageIcon(scaled));
                    imagePanel.add(robotLabel);
               } catch (IOException e) {
                    e.printStackTrace();
          return imagePanel;
      * This method initializes jTextField     
      * @return javax.swing.JTextField     
     private JTextField getScreenameTextField() {
          if (screenameTextField == null) {
               screenameTextField = new JTextField();
               screenameTextField.setBounds(22, 208, 168, 20);
               screenameTextField.addKeyListener(new java.awt.event.KeyAdapter() {  
                    public void keyTyped(java.awt.event.KeyEvent e) {
                         if (!isAllowedCharacter(e.getKeyChar())) {
                              e.consume();
                              Toolkit.getDefaultToolkit().beep();
                    public void keyPressed(java.awt.event.KeyEvent e) {
                         int keycode = e.getKeyCode();
                         if(keycode == KeyEvent.VK_ENTER && signonButton.isEnabled()) {
                              signonButton.doClick();
                              passwordTextField.setText("");
                         else if (keycode == KeyEvent.VK_ESCAPE) {
                              dispose();
                              System.exit(0);
                    public void keyReleased(java.awt.event.KeyEvent e) {
                         String screename = screenameTextField.getText();
                         char [] password = passwordTextField.getPassword();
                         if (screename.equals("") ||
                                   password.length <= 0) {
                              signonButton.setEnabled(false);
                         else if (!screename.equals("") &&
                                   password.length > 0) {
                              signonButton.setEnabled(true);
                         clearPasswordArray(password);
          return screenameTextField;
      * This method initializes jPanel1     
      * @return javax.swing.JPanel     
     private JPanel getJPanel1() {
          if (jPanel1 == null) {
               jPanel1 = new JPanel();
               jPanel1.setBounds(8, 173, 188, 1);
               jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(java.awt.Color.gray,5));
          return jPanel1;
      * This method initializes jPasswordField     
      * @return javax.swing.JPasswordField     
     private JPasswordField getPasswordTextField() {
          if (passwordTextField == null) {
               passwordTextField = new JPasswordField();
               passwordTextField.setBounds(20, 259, 170, 20);
               passwordTextField.addKeyListener(new java.awt.event.KeyAdapter() {
                    public void keyTyped(java.awt.event.KeyEvent e) {
                         if (!isAllowedCharacter(e.getKeyChar())) {
                              e.consume();
                              Toolkit.getDefaultToolkit().beep();
                    public void keyPressed(java.awt.event.KeyEvent e) {
                         int keycode = e.getKeyCode();
                         if(keycode == KeyEvent.VK_ENTER && signonButton.isEnabled()) {
                              signonButton.doClick();
                              passwordTextField.setText("");
                         else if (keycode == KeyEvent.VK_ESCAPE) {
                              dispose();
                              System.exit(0);
                    public void keyReleased(java.awt.event.KeyEvent e) {
                         String screename = screenameTextField.getText();
                         char [] password = passwordTextField.getPassword();
                         if (screename.equals("") ||
                                   password.length <= 0) {
                              signonButton.setEnabled(false);
                         else if (!screename.equals("") &&
                                   password.length > 0) {
                              signonButton.setEnabled(true);
                         clearPasswordArray(password);
          return passwordTextField;
      * This method initializes jContentPane
      * @return javax.swing.JPanel
     private javax.swing.JPanel getJContentPane() {
          if(jContentPane == null) {
               passwordLabel = new JLabel();
               screenameLabel = new JLabel();
               jContentPane = new javax.swing.JPanel();
               jContentPane.setLayout(null);
               screenameLabel.setBounds(22, 182, 132, 20);
               screenameLabel.setText("Screename");
               screenameLabel.setEnabled(true);
               screenameLabel.setFont(new java.awt.Font("Century Gothic", java.awt.Font.BOLD, 12));
               passwordLabel.setBounds(21, 238, 135, 17);
               passwordLabel.setText("Password");
               jContentPane.add(getImagePanel(), null);
               jContentPane.add(screenameLabel, null);
               jContentPane.add(getScreenameTextField(), null);
               jContentPane.add(getJPanel1(), null);
               jCon