import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import java.text.SimpleDateFormat;
 
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
 
public class FileTree2 
  extends JFrame 
{
  public static final ImageIcon ICON_COMPUTER = 
    new ImageIcon("computer.gif");
  public static final ImageIcon ICON_DISK = 
    new ImageIcon("disk.gif");
  public static final ImageIcon ICON_FOLDER = 
    new ImageIcon("folder.gif");
  public static final ImageIcon ICON_EXPANDEDFOLDER = 
    new ImageIcon("expandedfolder.gif");
 
  protected JTree  m_tree;
  protected DefaultTreeModel m_model;
  protected JTextField m_display;
 
// NEW
  protected JPopupMenu m_popup;
  protected Action m_action;
  protected TreePath m_clickedPath;
 
  public FileTree2()
  {
    super("Directories Tree [Popup Menus]");
    setSize(400, 300);
 
    DefaultMutableTreeNode top = new DefaultMutableTreeNode(
      new IconData(ICON_COMPUTER, null, "Computer"));
 
    DefaultMutableTreeNode node;
    File[] roots = File.listRoots();
    for (int k=0; k<roots.length; k++)
    {
      node = new DefaultMutableTreeNode(new IconData(ICON_DISK, 
        null, new FileNode(roots[k])));
      top.add(node);
      node.add(new DefaultMutableTreeNode( new Boolean(true) ));
    }
 
    m_model = new DefaultTreeModel(top);
    m_tree = new JTree(m_model);
 
                m_tree.putClientProperty("JTree.lineStyle", "Angled");
 
    TreeCellRenderer renderer = new 
      IconCellRenderer();
    m_tree.setCellRenderer(renderer);
 
    m_tree.addTreeExpansionListener(new 
      DirExpansionListener());
 
    m_tree.addTreeSelectionListener(new 
      DirSelectionListener());
 
    m_tree.getSelectionModel().setSelectionMode(
      TreeSelectionModel.SINGLE_TREE_SELECTION); 
    m_tree.setShowsRootHandles(true); 
    m_tree.setEditable(false);
 
    JScrollPane s = new JScrollPane();
    s.getViewport().add(m_tree);
    getContentPane().add(s, BorderLayout.CENTER);
 
    m_display = new JTextField();
    m_display.setEditable(false);
    getContentPane().add(m_display, BorderLayout.NORTH);
 
// NEW
    m_popup = new JPopupMenu();
    m_action = new AbstractAction() 
    { 
      public void actionPerformed(ActionEvent e)
      {
        if (m_clickedPath==null)
          return;
        if (m_tree.isExpanded(m_clickedPath))
          m_tree.collapsePath(m_clickedPath);
        else
          m_tree.expandPath(m_clickedPath);
      }
    };
    m_popup.add(m_action);
    m_popup.addSeparator();
 
    Action a1 = new AbstractAction("Delete") 
    { 
      public void actionPerformed(ActionEvent e)
      {
                                m_tree.repaint();
        JOptionPane.showMessageDialog(FileTree2.this, 
          "Delete option is not implemented",
          "Info", JOptionPane.INFORMATION_MESSAGE);
      }
    };
    m_popup.add(a1);
 
    Action a2 = new AbstractAction("Rename") 
    { 
      public void actionPerformed(ActionEvent e)
      {
                                m_tree.repaint();
        JOptionPane.showMessageDialog(FileTree2.this, 
          "Rename option is not implemented",
          "Info", JOptionPane.INFORMATION_MESSAGE);
      }
    };
    m_popup.add(a2);
    m_tree.add(m_popup);
    m_tree.addMouseListener(new PopupTrigger());
 
    WindowListener wndCloser = new WindowAdapter()
    {
      public void windowClosing(WindowEvent e) 
      {
        System.exit(0);
      }
    };
    addWindowListener(wndCloser);
 
    setVisible(true);
  }
 
  DefaultMutableTreeNode getTreeNode(TreePath path)
  {
    return (DefaultMutableTreeNode)(path.getLastPathComponent());
  }
 
  FileNode getFileNode(DefaultMutableTreeNode node)
  {
    if (node == null)
      return null;
    Object obj = node.getUserObject();
    if (obj instanceof IconData)
      obj = ((IconData)obj).getObject();
    if (obj instanceof FileNode)
      return (FileNode)obj;
    else
      return null;
  }
 
// NEW
  class PopupTrigger extends MouseAdapter
  {
    public void mouseReleased(MouseEvent e)
    {
      if (e.isPopupTrigger())
      {
        int x = e.getX();
        int y = e.getY();
        TreePath path = m_tree.getPathForLocation(x, y);
        if (path != null)
        {
          if (m_tree.isExpanded(path))
            m_action.putValue(Action.NAME, "Collapse");
          else
            m_action.putValue(Action.NAME, "Expand");
          m_popup.show(m_tree, x, y);
          m_clickedPath = path;
        }
      }
    }
  }
 
    // Make sure expansion is threaded and updating the tree model
    // only occurs within the event dispatching thread.
    class DirExpansionListener implements TreeExpansionListener
    {
        public void treeExpanded(TreeExpansionEvent event)
        {
            final DefaultMutableTreeNode node = getTreeNode(
                event.getPath());
            final FileNode fnode = getFileNode(node);
 
            Thread runner = new Thread() 
            {
              public void run() 
              {
                if (fnode != null && fnode.expand(node)) 
                {
                  Runnable runnable = new Runnable() 
                  {
                    public void run() 
                    {
                       m_model.reload(node);
                    }
                  };
                  SwingUtilities.invokeLater(runnable);
                }
              }
            };
            runner.start();
        }
 
        public void treeCollapsed(TreeExpansionEvent event) {}
    }
 
  class DirSelectionListener 
    implements TreeSelectionListener 
  {
    public void valueChanged(TreeSelectionEvent event)
    {
      DefaultMutableTreeNode node = getTreeNode(
        event.getPath());
      FileNode fnode = getFileNode(node);
      if (fnode != null)
        m_display.setText(fnode.getFile().
          getAbsolutePath());
      else
        m_display.setText("");
    }
  }
 
  public static void main(String argv[]) 
  {
    new FileTree2();
  }
}
 
class IconCellRenderer 
  extends    JLabel 
  implements TreeCellRenderer
{
  protected Color m_textSelectionColor;
  protected Color m_textNonSelectionColor;
  protected Color m_bkSelectionColor;
  protected Color m_bkNonSelectionColor;
  protected Color m_borderSelectionColor;
 
  protected boolean m_selected;
 
  public IconCellRenderer()
  {
    super();
    m_textSelectionColor = UIManager.getColor(
      "Tree.selectionForeground");
    m_textNonSelectionColor = UIManager.getColor(
      "Tree.textForeground");
    m_bkSelectionColor = UIManager.getColor(
      "Tree.selectionBackground");
    m_bkNonSelectionColor = UIManager.getColor(
      "Tree.textBackground");
    m_borderSelectionColor = UIManager.getColor(
      "Tree.selectionBorderColor");
    setOpaque(false);
  }
 
  public Component getTreeCellRendererComponent(JTree tree, 
    Object value, boolean sel, boolean expanded, boolean leaf, 
    int row, boolean hasFocus) 
 
  {
    DefaultMutableTreeNode node = 
      (DefaultMutableTreeNode)value;
    Object obj = node.getUserObject();
    setText(obj.toString());
 
                if (obj instanceof Boolean)
                  setText("Retrieving data...");
 
    if (obj instanceof IconData)
    {
      IconData idata = (IconData)obj;
      if (expanded)
        setIcon(idata.getExpandedIcon());
      else
        setIcon(idata.getIcon());
    }
    else
      setIcon(null);
 
    setFont(tree.getFont());
    setForeground(sel ? m_textSelectionColor : 
      m_textNonSelectionColor);
    setBackground(sel ? m_bkSelectionColor : 
      m_bkNonSelectionColor);
    m_selected = sel;
    return this;
  }
 
  public void paintComponent(Graphics g) 
  {
    Color bColor = getBackground();
    Icon icon = getIcon();
 
    g.setColor(bColor);
    int offset = 0;
    if(icon != null && getText() != null) 
      offset = (icon.getIconWidth() + getIconTextGap());
    g.fillRect(offset, 0, getWidth() - 1 - offset,
      getHeight() - 1);
 
    if (m_selected) 
    {
      g.setColor(m_borderSelectionColor);
      g.drawRect(offset, 0, getWidth()-1-offset, getHeight()-1);
    }
 
    super.paintComponent(g);
    }
}
 
class IconData
{
  protected Icon   m_icon;
  protected Icon   m_expandedIcon;
  protected Object m_data;
 
  public IconData(Icon icon, Object data)
  {
    m_icon = icon;
    m_expandedIcon = null;
    m_data = data;
  }
 
  public IconData(Icon icon, Icon expandedIcon, Object data)
  {
    m_icon = icon;
    m_expandedIcon = expandedIcon;
    m_data = data;
  }
 
  public Icon getIcon() 
  { 
    return m_icon;
  }
 
  public Icon getExpandedIcon() 
  { 
    return m_expandedIcon!=null ? m_expandedIcon : m_icon;
  }
 
  public Object getObject() 
  { 
    return m_data;
  }
 
  public String toString() 
  { 
    return m_data.toString();
  }
}
 
class FileNode
{
  protected File m_file;
 
  public FileNode(File file)
  {
    m_file = file;
  }
 
  public File getFile() 
  { 
    return m_file;
  }
 
  public String toString() 
  { 
    return m_file.getName().length() > 0 ? m_file.getName() : 
      m_file.getPath();
  }
 
  public boolean expand(DefaultMutableTreeNode parent)
  {
    DefaultMutableTreeNode flag = 
      (DefaultMutableTreeNode)parent.getFirstChild();
    if (flag==null)    // No flag
      return false;
    Object obj = flag.getUserObject();
    if (!(obj instanceof Boolean))
      return false;      // Already expanded
 
    parent.removeAllChildren();  // Remove Flag
 
    File[] files = listFiles();
    if (files == null)
      return true;
 
    Vector v = new Vector();
 
    for (int k=0; k<files.length; k++)
    {
      File f = files[k];
      if (!(f.isDirectory()))
        continue;
 
      FileNode newNode = new FileNode(f);
 
      boolean isAdded = false;
      for (int i=0; i<v.size(); i++)
      {
        FileNode nd = (FileNode)v.elementAt(i);
        if (newNode.compareTo(nd) < 0)
        {
          v.insertElementAt(newNode, i);
          isAdded = true;
          break;
        }
      }
      if (!isAdded)
        v.addElement(newNode);
    }
 
    for (int i=0; i<v.size(); i++)
    {
      FileNode nd = (FileNode)v.elementAt(i);
      IconData idata = new IconData(FileTree2.ICON_FOLDER, 
        FileTree2.ICON_EXPANDEDFOLDER, nd);
      DefaultMutableTreeNode node = new 
        DefaultMutableTreeNode(idata);
      parent.add(node);
 
      if (nd.hasSubDirs())
        node.add(new DefaultMutableTreeNode( 
          new Boolean(true) ));
    }
 
    return true;
  }
 
  public boolean hasSubDirs()
  {
    File[] files = listFiles();
    if (files == null)
      return false;
    for (int k=0; k<files.length; k++)
    {
      if (files[k].isDirectory())
        return true;
    }
    return false;
  }
 
  public int compareTo(FileNode toCompare)
  { 
    return  m_file.getName().compareToIgnoreCase(
      toCompare.m_file.getName() ); 
  }
 
  protected File[] listFiles()
  {
    if (!m_file.isDirectory())
      return null;
    try
    {
      return m_file.listFiles();
    }
    catch (Exception ex)
    {
      JOptionPane.showMessageDialog(null, 
        "Error reading directory "+m_file.getAbsolutePath(),
        "Warning", JOptionPane.WARNING_MESSAGE);
      return null;
    }
  }
}

public boolean isPopupTrigger()
Note: Popup menus are triggered differently on different systems. Therefore, isPopupTrigger should be checked in both mousePressed and mouseReleased for proper cross-platform functionality.