TreeSelectionListener with JPanel is not reacting

Question

Hi all!
I have class which extends JPanel, and is later docked in a side menu. The effect should be like the Tools menu in VisualStudio.
Inside the JPanel I have a JTree. And the TreeSelectionListener isn't working. I tried the JTree code in a plain project and it works. So I figure it's something to do with the JPanel.
Here my code with the JTree
package de.lmu.ifi.pst.swep.rid.gui;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Map;
import java.util.TreeMap;
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import com.vlsolutions.swing.docking.DockKey;
import com.vlsolutions.swing.docking.Dockable;
import de.lmu.ifi.pst.swep.rid.cartridgeInterface.AbstractCartridgeElement;
import de.lmu.ifi.pst.swep.rid.cartridgeInterface.AbstractModelElement;
import de.lmu.ifi.pst.swep.rid.cartridgeInterface.ICartridge;
import de.lmu.ifi.pst.swep.rid.cartridgeloader.CartridgeLoader;
import de.lmu.ifi.pst.swep.rid.cartridgeloader.ComponentLoader;
import de.lmu.ifi.pst.swep.rid.interfaces.ICartridgeBay;
import de.lmu.ifi.pst.swep.rid.utils.IconProvider;
import de.lmu.ifi.pst.swep.rid.utils.Settings;
import de.lmu.ifi.pst.swep.rid.utils.IconProvider.Identifier;
* The toolbar for selecting canvas tools, such as select and new Cartridge
* Element creation.
public class CartridgeToolbar extends JPanel implements Dockable, ICartridgeBay {
     static {
          Settings.register("cartridge.selection.none", false);
          Settings.register("cartridge.selection.default", true);
          Settings.register("cartridge.selection.user", false);
          Settings.register("cartridge.selection.xul", true);
          Settings.register("cartridge.selection.uml", true);
     private static final long serialVersionUID = 8926943523499013449L;
     private DockKey dockKey = new DockKey("cartridgeToolbar", "Tools", null, IconProvider
               .getSmallImage(Identifier.VIEW_TOOLS));
     private Map<String, ArrayList<AbstractCartridgeElement>> cartridgeGroups = new TreeMap<String, ArrayList<AbstractCartridgeElement>>();
     private JTree cartridgeTree;
     public CartridgeToolbar(ComponentLoader componentLoader) {
          super();
          dockKey.setFloatEnabled(true);
          dockKey.setMaximizeEnabled(false);
          dockKey.setResizeWeight(0.1f);          
          this.setLayout(new BorderLayout());          
          setPreferredSize(new Dimension(200, 600));
          cartridgeTree = new JTree(new DefaultMutableTreeNode("Unpainted tree"));
          DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer();
             renderer.setOpenIcon(null);
             renderer.setClosedIcon(null);
             renderer.setLeafIcon(null);
             cartridgeTree.setCellRenderer(renderer);
          cartridgeTree.putClientProperty("JTree.lineStyle", "None");
          DefaultTreeSelectionModel selectionModel = new DefaultTreeSelectionModel();
             selectionModel.setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
          cartridgeTree.setSelectionModel(selectionModel);
          fillTreeWith("cartridgexul.xml");
          fillTreeWith("cartridgeuml.xml");
          cartridgeTree.getSelectionModel().addTreeSelectionListener(new TreeSelectionListener() {//FIXME: listener not working
               @Override
               public synchronized void valueChanged(TreeSelectionEvent e) {
                  DefaultMutableTreeNode node = (DefaultMutableTreeNode) e.getPath().getLastPathComponent();
                  System.out.println("You selected " + node);
          cartridgeTree.putClientProperty("JTree.lineStyle", "None");
          cartridgeTree.setSelectionModel(null);
          JScrollPane scrollPane = new JScrollPane(cartridgeTree);
          this.add(scrollPane, BorderLayout.CENTER);
      * Method returns the name of the currently selected Cartridge Element that is to be drawn on the canvas
      * @return
      *           Name of the selected cartridge element.
     public String getSelectedElement()
        //TODO: if inner node
          return cartridgeTree.getLastSelectedPathComponent().toString();          
     private void fillTreeWith(String cartrigdeFileName)
          File dir = new File(".");
          String rootPath;
          try {
               rootPath = dir.getCanonicalPath() + File.separator + "resources";
               addCartridge(rootPath, cartrigdeFileName);
          } catch (IOException e) {
               e.printStackTrace();
     public void addCartridge(String rootPath, String cartrigdeFileName) {
          CartridgeLoader catridgeLoader = new CartridgeLoader(rootPath, cartrigdeFileName);
          ICartridge cartridgeInterface = catridgeLoader.loadCartridge();
          final String nameCartridge = cartridgeInterface.getCartridgeName();
          ArrayList<AbstractCartridgeElement> catridgeGroupElements = generateFactories(cartridgeInterface);
          DefaultMutableTreeNode root = (DefaultMutableTreeNode) cartridgeTree.getModel().getRoot();
          DefaultMutableTreeNode cartridgeGroupNode= new DefaultMutableTreeNode(nameCartridge);
          DefaultMutableTreeNode elementNode ;
          DefaultMutableTreeNode subElementNode;
          for (AbstractCartridgeElement element : catridgeGroupElements) {
               elementNode = new DefaultMutableTreeNode(element.getElementName());//TODO: add icon
               subElementNode = new DefaultMutableTreeNode(element.getElementName() + "1");
               elementNode.add(subElementNode);
               subElementNode = new DefaultMutableTreeNode(element.getElementName() + "2");
               elementNode.add(subElementNode);
                  cartridgeGroupNode.add(elementNode);//TODO: add subType          
          root.add(cartridgeGroupNode);
          cartridgeGroups.put(cartridgeInterface.getCartridgeName(), catridgeGroupElements);
      * With getting a new cartridge interface the method will be able to create
      * all factories of the cartridge interface. Element factories are used to
      * add new elements to the canvas.
      * @return List of factories belonging to a cartridge interface
     private ArrayList<AbstractCartridgeElement> generateFactories(ICartridge cartridgeInterface) {
          ArrayList<AbstractCartridgeElement> cartridgeGroupElements = new ArrayList<AbstractCartridgeElement>();
          for (Enumeration<Integer> el = cartridgeInterface.getElementIDs(); el.hasMoreElements();) {
               cartridgeGroupElements.add(cartridgeInterface.getElementFactoryByID((Integer) el.nextElement()));
          return cartridgeGroupElements;
     @Override
     public DockKey getDockKey() {
          return dockKey;
     @Override
     public AbstractModelElement createCartridgeElement(String id) {
          // getElementFactoryByID
          return null;
     @Override
     public Component getComponent() {
          // TODO Auto-generated method stub
          return null;
     @Override
     public JComponent getComponent(String path, String cartridgeName) {
          // TODO Auto-generated method stub
          return null;
     @Override
     public void setButtonGroup(ButtonGroup buttongroup) {
          // TODO Auto-generated method stub
}The most important is ofcourse the constructor. Any suggestions and help would be greatly apprieciated.
best of all,
Szymon

Answer 1

cartridgeTree.setSelectionModel(null);You creating a new selection model, add it to the tree and add a listener to it. Then you throw it away.