package example;
 
import javax.swing.*;
import javax.swing.tree.*;
import java.io.*;
 
public class Window extends javax.swing.JFrame {
    private DefaultTreeModel model ;
    private DefaultMutableTreeNode root; 
 
    private void showDir (DefaultMutableTreeNode target , File dir)
    {
        File [] a = dir.listFiles();
        for (File t : a)
        {
            DefaultMutableTreeNode item = 
                    new DefaultMutableTreeNode (t.getName());
            if (t.isDirectory())
                showDir (item, t);
            target.add (item);
        }
    }
 
    public Window() {
        initComponents();
        File f = new File ("..");
        root =  new DefaultMutableTreeNode (f.getAbsoluteFile());
        showDir (root, f);
        model = new DefaultTreeModel (root);
        jTree1.setModel (model);
    }
 
    private void jTree1ValueChanged(javax.swing.event.TreeSelectionEvent evt) {                                    
       for (TreePath p : evt.getPaths())
       {
           Object obj = p.getLastPathComponent();
           if (obj instanceof DefaultMutableTreeNode)
           {
               DefaultMutableTreeNode node = (DefaultMutableTreeNode) obj;
               String s = (String) node.getUserObject();
               this.setTitle(s);
           }
       }
    }                                   
}

package example;
 
import javax.swing.*;
import javax.swing.tree.*;
import java.io.*;
 
public class Window extends javax.swing.JFrame {
 
    private DefaultTreeModel model ;
    private DefaultMutableTreeNode root; 
 
    public Window() {
        initComponents();
 
        File f = new File (".");
        root =  new DefaultMutableTreeNode (f.getAbsoluteFile());
 
        String [] a = f.list();
        for (int i = 0; i < a.length; i++)
        {
            DefaultMutableTreeNode item = 
                    new DefaultMutableTreeNode (a[i]);
            root.add (item);
        }
 
        model = new DefaultTreeModel (root);
        jTree1.setModel (model);
   }
}