Implementing listener in JTree

Hi,
I am trying to implement a listener for JTree within a class other than the one where is tree is initialized and set. With this listener, I would like to grab the index of the selected child from a tree. Do I only need to implement void ValueChanged() or is there something else that is missing because it is not working. Hope you can help me. Thanks.
Here is what I am doing:
//Declaration of class
public class ServerJobList extends JTree implements TreeSelectionListener
//Listener
public void valueChanged(TreeSelectionEvent e) {
          DefaultMutableTreeNode node = (DefaultMutableTreeNode)
          getLastSelectedPathComponent();
if (node == null) return;
if(node.isLeaf()){
     DefaultMutableTreeNode parent=(DefaultMutableTreeNode)node.getParent();
//Get index of selected item from tree.
selectedIndex=parent.getIndex(node);
String sServer=parent.toString();
zServer=Document.getClient().getServerList().getServerByName(sServer);
displayInfoList(selectedIndex);
//Testing....
System.out.println(sServer + "'s index= " + selectedIndex);

May someone please help me with this question. I am getting headaches trying to figure out what could be going wrong? Thanks.

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Nevermind, I solved it by my self :)
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I'm writing a simple Swing program to examine the entries in a JAR file as a JTree. It is not meant to be professional grade, it's simply for my own fun.
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<pre>
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</pre>
Thanks!
Kevin Yetman

Without looking at all your code, I would suggest that you only redraw the part of the tree that changes (addition or deletion of nodes). To do this, you can call a method of DefaultTreeModel, nodeStructureChanged(TreeNode nodeThatChanged). This fires the appropriate event which in turn causes the node and only its descendents to be redrawn. Good luck.
-Matt

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See the Article
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http://www.javaworld.com/javaworld/javatips/jw-javatip97.html
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These tutorials were indeed very helpful!
And imagine that I had found the cut-paste tutorial, but since it didn't mention anything about JTrees, I ignored it... :P
Anyway, since I had this problem for some days now, I think you deserve the duke dollars!!!! :)))

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Hello,
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From : [email protected]

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// Fetch any numbered child of a node for the JTree.
// Our model returns File objects for all nodes in the tree. The
// JTree displays these by calling the File.toString() method.
public Object getChild(Object parent, int index) {
String[] children = ((JFile)parent).list();
if ((children == null) || (index >= children.length)) return null;
return new JFile((JFile)parent,children[index]);
// Figure out a child's position in its parent node.
public int getIndexOfChild(Object parent, Object child) {
String[] children = ((File)parent).list();
if (children == null) return -1;
String childname = ((File)child).getName();
for(int i = 0; i < children.length; i++) {
if (childname.equals(children)) return i;
return -1;
// This method is invoked by the JTree only for editable trees.
// This TreeModel does not allow editing, so we do not implement
// this method. The JTree editable property is false by default.
public void valueForPathChanged(TreePath path, Object newvalue) {}
// Since this is not an editable tree model, we never fire any events,
// so we don't actually have to keep track of interested listeners
public void addTreeModelListener(TreeModelListener l) {}
public void removeTreeModelListener(TreeModelListener l) {}
class TreeBar implements ActionListener{
public JTree tree = new JTree();
public File[] roots = File.listRoots();
JToolBar toolbar = new JToolBar();
public TreeBar(){
FileTreeModel model = new FileTreeModel(new JFile(System.getProperty("user.home")));
tree.setModel(model);
tree.setCellRenderer(new MyRenderer());
public JToolBar CreatingTreeBar(){
for(int i=0;i<roots.length;i++){
JButton button = new JButton(roots[i].getPath(),new MyRenderer().inicon);
button.addActionListener(this);
button.setActionCommand(roots[i].getPath());
toolbar.add(button);
toolbar.setFloatable(false);
toolbar.setRollover(true);
return(toolbar);
public void actionPerformed(java.awt.event.ActionEvent e) {
FileTreeModel model = new FileTreeModel(new JFile(e.getActionCommand()));
tree.setModel(model);
class MyRenderer extends DefaultTreeCellRenderer {
ImageIcon inicon = createImageIcon("1.gif");
ImageIcon exicon = createImageIcon("2.gif");
ImageIcon leaficon = createImageIcon("3.gif");
public ImageIcon createImageIcon(String path) {
java.net.URL imgURL = TreeIconDemo2.class.getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL);
} else {
System.err.println("Couldn't find file: " + path);
return null;
public Component getTreeCellRendererComponent(
JTree tree,
Object value,
boolean sel,
boolean expanded,
boolean leaf,
int row,
boolean hasFocus) {
super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf, row, hasFocus);
if (leaf){
setIcon(leaficon);
}else
if(expanded)
setIcon(exicon);
else
setIcon(inicon);
return this;
class JFile extends File{
public JFile(String path){
super(path);
public JFile(File parent,String child){
super(parent,child);
public String toString(){
FileSystem fs = new FileSystem();
if(fs.isFileSystemRoot(this))
return(this.getPath());
else
return(fs.getSystemDisplayName(this));
class FileSystem extends FileSystemView{
public File createNewFolder(File containingDir) throws java.io.IOException {
return(this.createFileObject(containingDir,"harish"));

Asynchronous Queue listener - stale connection.

Tom,
          I have an asynchronous listener for a remote distributed queue (4 jms servers). The listener process is running which had connected with the queue say 10-12 hours ago. The problem I have is, once message comes to one of the queue, even though listener has not lost the connection (as nothing comes in logs and ExceptionListener is implemented), Listener doesnt pickup the message. why?
          we are using WL 8.1 right now.
          Thanks,
          Malav

You need to either ensure that the there's a listener on every distributed queue member, or configure the distributed queue to automatically forward messages from idle queues to queues that have consumers ("queue forwarding").
          Tom

Problem with new window opening with basic test JTree program

I'm still getting to grips with Swing, and have now moved on to basic JTrees.
I'm currently trying to use an add and delete button to add new nodes to the root etc. The addition and deletion is working ok, except that each time the addButton is pressed, a completely new window is created on top of the current window with the new node added to the root etc.
I know this is probably a simple mistake, but I can't quite see it at the moment.
My current code is as follows,
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
public class TreeAdditionDeletionTester_1 extends JFrame implements ActionListener
    private JTree tree;
    private DefaultTreeModel treeModel;
    private DefaultMutableTreeNode rootNode;
    private JButton addButton;
    private JButton deleteButton;
    private JPanel panel;
    private int newNodeSuffix = 1;
    private static String Add_Command = "Add Node";
    private static String Delete_Command = "Remove Node";
    //DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Root");
    //TreeAdditionDeletionTester_1 treeChange;
    public TreeAdditionDeletionTester_1()
        setTitle("Tree with Add and Remove Buttons");
        //DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Root");
        rootNode = new DefaultMutableTreeNode("Root");
        treeModel = new DefaultTreeModel(rootNode);
        tree = new JTree(treeModel);
        tree.setEditable(false);
        tree.setSelectionRow(0);
        JScrollPane scrollPane = new JScrollPane(tree);
        getContentPane().add(scrollPane, BorderLayout.CENTER);
        JPanel panel = new JPanel();
        addButton = new JButton("Add Node");
        addButton.setActionCommand(Add_Command);
        addButton.addActionListener(this);
        panel.add(addButton);
        getContentPane().add(panel, BorderLayout.SOUTH);
        deleteButton = new JButton("Delete Node");
        deleteButton.setActionCommand(Delete_Command);
        deleteButton.addActionListener(this);
        panel.add(deleteButton);
        getContentPane().add(panel, BorderLayout.SOUTH);
        setSize(300, 400);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    public void actionPerformed(ActionEvent event)
       TreeAdditionDeletionTester_1 treeChange = new TreeAdditionDeletionTester_1();
        String command = event.getActionCommand();
        if (Add_Command.equals(command)) {
            //Add button clicked
            treeChange.addObject("New Node " + newNodeSuffix++);
        } if (Delete_Command.equals(command)) {
            //Remove button clicked
            treeChange.removeCurrentNode();
    public void removeSelectedNode()
        //get the selected node
        DefaultMutableTreeNode selNode = (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();
        //method from Class JTree
        if (selNode != null)
            //get the parent of the selected node
            MutableTreeNode parent = (MutableTreeNode)(selNode.getParent());
            //getParent() from Interface TreeNode
            // if the parent is not null
            if (parent != null)
                //remove the node from the parent
                treeModel.removeNodeFromParent(selNode);//method from Class DefaultTreeModel
                return;
    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,
                                            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 new node.
        if (shouldBeVisible) {
            tree.scrollPathToVisible(new TreePath(childNode.getPath()));
        return childNode;
    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
                                            Object child) {
        return addObject(parent, child, false);
    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;
     * Main method to run as an Application
    public static void main(String[] arg)
        TreeAdditionDeletionTester_1 addDeleteTree = new TreeAdditionDeletionTester_1();
}      Thanks.

I'm currently trying to use an add and delete button
to add new nodes to the root etc. The addition and
deletion is working ok, except that each time the
addButton is pressed, a completely new window is
created on top of the current window with the new
node added to the root etc.
I know this is probably a simple mistake, but I can't
quite see it at the moment.
Look at the actionPerformed code for your buttons. The first thing you do there is to create a new TreeAdditionDeletionTester_1, so I don't know why you are surprised you get a new window. There is no need to create a new instance in there, just call addObject/removeCurrentNode on the "this" instance.

DnD from JTree to JTable

Hi guys,
It seems JTree DnD support is a quit difficult feature to implement of all swing components.
I'm writing an application in which I have a JTree structure representing the file system of user machine and another JTable component at the right.
I want to be able to drag files nodes from left JTree to right JTable.
I would appreciate a lot if someone share with me some source code examples for this functionality.
can someone post some basic java code to get me started or point me to some web resource discussing this feature?
thanks much.

http://forum.java.sun.com/thread.jspa?threadID=296255Thank you. I already looked at this thread but it's not what i'm looking for: it shows dnd from a JTree to another JTree..however i need to implement dnd from JTree to JTable.
Is there some basic example on how to do that ?
thanks.

Help with Jtree for a file navigator

Hi there,
I'm trying to do something with a JTree, but I can't find anywhere how to perform that.
I'm making a little file explorer, with a JTree to navigate through the file structure. I have also two buttons (up and back). When I select a directory with the mouse, the corresponding node is highlighted, but when I push the button up, or the button back, it isn't (I mean, the directory is caught well, but no nodes are highlighted). It uses the DefaultTreeCellRenderer
Any ideas to highlight the directory when I push the up or back button?.
Thank you very much!!!!

Strange. Does this small, simplified example work for you?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Xxx extends JFrame implements ActionListener {
private JTree tree = new JTree();
private JButton butt = new JButton("!");
public static void main(String[] args) {
    new Xxx();
public Xxx() {
    getContentPane().add(new JScrollPane(tree), BorderLayout.CENTER);
    getContentPane().add(butt, BorderLayout.SOUTH);
    butt.addActionListener(this);
    pack();
    setVisible(true);
public void actionPerformed(ActionEvent e) {
    int[] rows = tree.getSelectionRows();
    if ((rows != null) && (rows.length == 1)) {
      int next = rows[0] + 1;
      if (next >= tree.getRowCount()) {
        next = 0;
      tree.setSelectionRow(next);
}

Horizontal JTree

I think I'm beating a dead horse with this one.... all previous posts to the forums have been more or less fruitless (aside from do-it-yerself)
BUT! Does anyone know of a publicly available implementation of a Horizontal JTree or something like it?
I'd really like something that looks similarly:
                                [Node1] [Node2] [Node3]
                                                     |
                         |       |       |      |      |      |
                      [Node3a]   |    [Node3c] |   [Node3e] |
                         |    [Node3b]       [Node3d]      [Node3f]
                         |
                             |       |      |      |      |
                          ....etc....Thanks,
--Spencer

Looking through the JTree API, I found in javax.swing.tree the RowMapper interface, which is implemented by various *LayoutCache classes.
How do you use these, and extending one of these classes a possible/easier solution to implementing a horizontal JTree apart from reimplementing JTree and all its inards?
Thanks,
--Spencer

Implementing listener in JTree

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