Problem rendering tree nodes of tree sent to applet from servlet

Hi,

I have an applet and a servlet and a DefaultMutableTreeNode being sent serialized from the servlet to the applet. In the servlet, the root has children of DefaultMutableTreeNodes with Result objects as UserObjects. The JTree in the applet should display the nodes of the root as different colored icons, see MyRenderer. The problem is that in the code in MyRenderer, the getUserObject object is not instanceOf Result, and only displays the dummy (yellow) icon. The getUserObject is null...

When I test with a root node with DFMTreeNode children with Result objects as UserObjects in the applet code, the tree displays with correct colored icons.

The Result.class exists both on server and client side in my deployment.
Why is getUserObject null? How can I get the nodes to render correctly?
Greatful for help - thanks in advance!


CLIENT SIDE:

package result;

import gp.triacq.qc.web.site.style.QCTheme;

import javax.swing.*;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultMutableTreeNode;
import java.awt.*;

public class TreePanel extends JPanel {

  private JTree _tree;
  private TestApplet _parent;

  public TreePanel(TestApplet parent) {
    super();
    _parent = parent;
    setLayout(new BorderLayout());

    DefaultMutableTreeNode root = new DefaultMutableTreeNode(new Result("Root", 2));
    DefaultMutableTreeNode child_1 = new DefaultMutableTreeNode(new Result("Result 1", 2));
    DefaultMutableTreeNode child_2 = new DefaultMutableTreeNode(new Result("Result 2", 3));
    DefaultMutableTreeNode child_11 = new DefaultMutableTreeNode(new Result("Result 4", 1));
    DefaultMutableTreeNode child_12 = new DefaultMutableTreeNode(new Result("Result 5", 2));
    DefaultMutableTreeNode child_21 = new DefaultMutableTreeNode(new Result("Result 6", 1));
    DefaultMutableTreeNode child_22 = new DefaultMutableTreeNode(new Result("Result 7", 1));
    root.add(child_1);
    root.add(child_2);
    child_1.add(child_11);
    child_1.add(child_12);
    child_2.add(child_21);
    child_2.add(child_22);
    _tree = new JTree(root);
    _tree.setRootVisible(false);
    _tree.setShowsRootHandles(true);
    _tree.setCellRenderer(new MyRenderer(_parent.getGreenIcon(), _parent.getRedIcon(), _parent.getYellowIcon()));
 
   add(_tree);
  }

  public void updateTree(DefaultMutableTreeNode root) {
    if (root != null) {
      if (_tree != null) {
        remove(_tree);
      }
      _tree = new QCTree(root);
      _tree.setRootVisible(false);
      _tree.setShowsRootHandles(true);
      _tree.setCellRenderer(new MyRenderer(_parent.getGreenIcon(), _parent.getRedIcon(), _parent.getYellowIcon()));
      add(_tree);
    } else {
      JLabel label = new JLabel("No result tree structure is available");
    }
  }

  private class MyRenderer extends DefaultTreeCellRenderer {

    private ImageIcon _greenIcon;
    private ImageIcon _redIcon;
    private ImageIcon _yellowIcon;

    public MyRenderer(ImageIcon greenIcon, ImageIcon redIcon, ImageIcon yellowIcon) {
      _greenIcon = greenIcon;
      _redIcon = redIcon;
      _yellowIcon = yellowIcon;
    }

    public Component getTreeCellRendererComponent(JTree tree, Object value, boolean sel, boolean expanded,
                                                  boolean leaf, int row, boolean hasFocus) {


      ResultComponent item;

      super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf, row, hasFocus);
      DefaultMutableTreeNode node = (DefaultMutableTreeNode) value;
      Object temp = node.getUserObject();

      // Debug
      if (temp == null) {
        System.out.println("temp = null"); // This is run for nodes of root from servlet
      } else {
        System.out.println("temp getClass = " + temp.getClass()); // This is run for nodes of root in applet (getClass = result.Result)
      }

      if (temp instanceof Result) {
        item = (Result)temp;

        if (item.getValue() == 1) {
          if (_greenIcon != null) {
            setIcon(_greenIcon);
          }
        }
        if (item.getValue() == 2) {
          if (_redIcon != null) {
            setIcon(_redIcon);
          }
        }
        if (item.getValue() == 3) {
          if (_yellowIcon != null) {
            setIcon(_yellowIcon);
          }
        }

      } else {
        if (_yellowIcon != null) {
          setIcon(_yellowIcon);     // Only this statement is run
        }
      }
      return this;
    }
  }
}


SERVER SIDE


package result;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Vector;
import javax.swing.tree.*;

public class TestServlet extends HttpServlet {

  public void init() {
  }

  public void doPost(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException {  

    // Hanle request for applet

    // Tree to return to applet
    Vector roots = new Vector();
    DefaultMutableTreeNode root = new DefaultMutableTreeNode(new Result("Root", 0));
    DefaultMutableTreeNode n1 = new DefaultMutableTreeNode(new Result("A", 0));
    DefaultMutableTreeNode n2 =  new DefaultMutableTreeNode(new Result("B", 1));
    DefaultMutableTreeNode n3 = new DefaultMutableTreeNode(new Result("C", 2));
    n1.add(new DefaultMutableTreeNode(new Result("A 1", 0)));
    n1.add(new DefaultMutableTreeNode(new Result("A 2", 1)));
    n2.add(new DefaultMutableTreeNode(new Result("B 1", 2)));
    n3.add(new DefaultMutableTreeNode(new Result("C 1", 3)));
   
    // Vector with the root object sent to applet
    try {
       ObjectOutputStream outputToApplet = new ObjectOutputStream(response.getOutputStream());
       outputToApplet.writeObject(roots);
       outputToApplet.flush();
       outputToApplet.close();
   } catch(Exception x) {
      x.printStackTrace();
   }
}