Jtree's ValueChange method problem

Question

my code are as follow:
i'm now doing a JTree which will list all the directory in the computers(every node is a directory) ..
When i click on each node, i wanna it to display all files names in this directory ...
but i just fail that statement:
DefaultMutableTreeNode node = (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();
this statement will cause an error
anyone know how to solve it ??
Thanks very very much !!!
my codes:
import java.io.*;
import javax.swing.*;
import java.awt.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.util.*;
import java.awt.event.*;
public class PDThumnailer extends JFrame {
     private JTree tree;
     private JScrollPane scpTree;
     private JSplitPane split;
     private JPanel leftPane;
     public PDThumnailer() {
          super();
          Vector dirs = new Vector();
          File[] roots = File.listRoots();
          for(int i=0; i<roots.length; i++) {
               dirs.add(roots);
          leftPane = new JPanel();
          tree = new JTree(new FileTreeModel(dirs));
          tree.setCellRenderer(new FileTreeCellRenderer());
          tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
          scpTree = new JScrollPane(tree);
          split = new JSplitPane(1, scpTree, leftPane);
          split.setOneTouchExpandable(true);
split.setDividerLocation(200);
          this.getContentPane().add(split);
          this.setSize(550,400);
          this.setVisible(true);
          this.addWindowListener(new WindowAdapter() {
                    public void windowClosing(WindowEvent e) {
                         //setVisible(false);
                         System.exit(-1);
          tree.addTreeSelectionListener(new TreeSelectionListener() {
                    public void valueChanged(TreeSelectionEvent e) {
                              DefaultMutableTreeNode node = (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();
                              if (node == null)
                                   return;
                              Object nodeInfo = node.getUserObject();
                              System.out.println("nodeInfo");
                              if(nodeInfo instanceof File) {
                                   File file = (File) nodeInfo;
                                   File[] allFiles = file.listFiles();
                                   for(int i=0;i<allFiles.length;i++)
                                        System.out.println(allFiles[i].getName());
     public static void main(String[] arg){
               new PDThumnailer();
class FileTreeCellRenderer extends JLabel implements TreeCellRenderer {
public FileTreeCellRenderer() {
     super("", JLabel.LEFT);
     this.setOpaque(true);
/* implements TreeCellRenderer BEGIN */
public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
     if (selected) {
          this.setBackground(Color.black);
          this.setForeground(Color.white);
     else {
          this.setBackground(Color.white);
          this.setForeground(Color.black);
     if (value instanceof File) {
          File file = (File) value;
          if (file.isDirectory()) {
                    this.setText(file.getPath());
                    this.setIcon(new ImageIcon("icon/folder.gif"));
          else {
                    this.setText(file.getName());
                    this.setIcon(new ImageIcon("icon/file.gif"));
     else {
               setText("");
     return this;
/* implements TreeCellRenderer END */
class FileTreeModel implements TreeModel {
private Vector dirs;
public FileTreeModel(Vector dirs) {
this.dirs = dirs;
/* implements TreeModel BEGIN */
public void addTreeModelListener(TreeModelListener l) {
public Object getChild(Object parent, int index) {
if (parent instanceof Vector) {
return dirs.get(index);
else if (parent instanceof File) {
File file = (File) parent;
if (file.isDirectory()) {
File[] allFiles = file.listFiles(new DirectoryFilter());
if (allFiles != null) {
          return allFiles[index];
return null;
public int getChildCount(Object parent) {
if (parent instanceof Vector) {
return dirs.size();
else if (parent instanceof File) {
File file = (File) parent;
if (file.isDirectory()) {
File[] allFiles = file.listFiles(new DirectoryFilter());
     int count =0;
if (allFiles != null) {
return allFiles.length;
return 0;
public int getIndexOfChild(Object parent, Object child) {
     if (parent instanceof Vector) {
          return dirs.indexOf(child);
     else if (parent instanceof File) {
          File file = (File) parent;
               if (file.isDirectory()) {
                         File[] allFiles = file.listFiles(new DirectoryFilter());
                         if (allFiles != null) {
                              for (int i=0; i<allFiles.length; i++) {
                                   if (child.equals(allFiles[i])) {
                                             return i;
     return -1;
public Object getRoot() {
return this.dirs;
public boolean isLeaf(Object node) {
     if (node instanceof Vector) {
          return dirs.isEmpty();
     else if (node instanceof File) {
     File file = (File) node;
     if (file.isDirectory()) {
               File[] allFiles = file.listFiles(new DirectoryFilter());
               if (allFiles != null) {
                    return allFiles.length == 0;
     return true;
public void removeTreeModelListener(TreeModelListener l) {
public void valueForPathChanged(TreePath path, Object newValue) {
/* implements TreeModel END */
class DirectoryFilter implements FileFilter
     public boolean accept(File f) {
          return f.isDirectory();

Answer 1

Replace this line with
DefaultMutableTreeNode node = (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();
DefaultMutableTreeNode node = (DefaultMutableTreeNode)(event.getPath().getLastPathComponent());Tell me whether that helps to solve your problem.