Problems updating gui in JApplet

Question

Hi,
I have a JApplet with a JPanel with another JPanel ? TreePanel ? containing a JScrollPane with a JTree.
When init() is run in MyApplet, treePanel is initiated with a JTree, with test data hardcoded in TreePanel?s constructor. I want the tree to change every time a thread loops, by calling method treePanel.updateResultTree(root) from the thread, with a new root. To test this, I have hardcoded a new tree content in the thread to pass to the TreePanel. In method updateResultTree(root), I remove the existing JTree from JScrollPane and add a new JTree to it, with the new root. Then I repaint the JScrollPane.
When I run the applet, the initial tree is displayed, but it is not updated with the new JTree for the first thread loop as expected. How is the gui in a JApplet refreshed/updated?? Will SwingWoker update the gui automatically without forcing repaint()?
Please help, I'm so stuck! Thanks in advance!
MyApplet
public class MyApplet extends JApplet {
   private TreePanel _treePanel;
   private UpdateHandler _updateHandler;
   private Thread _updateThread;
   public void init() {
      super.init();
      _treePanel = new TreePanel();
      // Updating thread
      _updateHandler = new UpdateHandler();
      _updateThread = new Thread(_updateHandler);
      _updateThread.start();
      // Initialize gui
      JPanel bigPanel = new JPanel();
      bigPanel.setLayout(new BoxLayout(bigPanel, BoxLayout.X_AXIS));          
      getContentPane().add(bigPanel, BorderLayout.CENTER);   
      _treePanel = new JPanel();
      bigPanels.add(_treePanel);
   // Updates the GUI every X seconds
   private class UpdateHandler implements Runnable {
      public final static int UPDATE_INTERVAL = 10;
      public UpdateHandler() { }
      public void run() {
         try {
            _displayResults();
         } catch (InterruptedException ie) {
   private synchronized void _ displayResults () throws InterruptedException {
      while(true) {
         // Resolve a new DefaultMutableTreeNode object as root to be updated in GUI
         // (For test)
         DefaultMutableTreeNode root = new DefaultMutableTreeNode(new Result("Root"));
         DefaultMutableTreeNode child_1 = new DefaultMutableTreeNode(new Result("Result X"));
         DefaultMutableTreeNode child_2 = new DefaultMutableTreeNode(new Result("Result Y"));
         DefaultMutableTreeNode child_11 = new DefaultMutableTreeNode(new Result("Result X1"));
         root.add(child_1);
         root.add(child_2);
         child_1.add(child_11);
         // Update the GUI 
         _treePanel.updateTree(root);
         wait(UPDATE_INTERVAL*1000);
}TreePanel
public class TreePanel extends JPanel {
   private JScrollPanel _treeSrcoll;
   private JTree _tree;
   TreePanel() {
      super();
      // Test tree, displayed in applet?s init()
      DefaultMutableTreeNode root = new DefaultMutableTreeNode (new Result("Root"));
      DefaultMutableTreeNode child_1 = new DefaultMutableTreeNode (new Result("Result 1"));
      DefaultMutableTreeNode child_2 = new DefaultMutableTreeNode (new Result("Result 2"));
      DefaultMutableTreeNode child_11 = new DefaultMutableTreeNode (new Result("Result 4"));
      DefaultMutableTreeNode child_12 = new DefaultMutableTreeNode (new Result("Result 5"));   
      root.add(child_1);
      root.add(child_2);
      child_1.add(child_11);
      child_1.add(child_12);
      _tree = new JTree(root);
      _treeScroll = new JScrollPane(_tree);
      add(_treeScroll, BorderLayout.CENTER);
   public void updateTree(DefaultMutableTreeNode  theRoot) {
      if (theRoot != null) {
         if (_tree!= null) {
            _treeScroll.remove(_tree);
         _ tree = new QCTree(root);     
         _treeScroll.add(_tree);
      } else {
         JLabel label = new JLabel("No result tree structure is available");
        _treeScroll.add(label);
     _treeScroll.repaint();
}Result
public class Result {
   private String _name; 
   public Result(String name) {
      _name = name;
   public String toString() {
      return _name;

Answer 1

I found the error:
I need to use
treeScroll.getViewPort().add(tree);
and
treeScroll.getViewPort().remove(tree);