JCheckBox付きJTreeでディレクトリ構造を表示

class CheckBoxNodeEditor extends TriStateCheckBox implements TreeCellEditor {
  private final FileSystemView fileSystemView;
  private final JPanel panel = new JPanel(new BorderLayout());
  private DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer();
  private File file;

  public CheckBoxNodeEditor(FileSystemView fileSystemView) {
    super();
    this.fileSystemView = fileSystemView;
    this.addActionListener(new ActionListener() {
      @Override public void actionPerformed(ActionEvent e) {
        stopCellEditing();
      }
    });
    panel.setFocusable(false);
    panel.setRequestFocusEnabled(false);
    panel.setOpaque(false);
    panel.add(this, BorderLayout.WEST);
    this.setOpaque(false);
  }

  @Override public Component getTreeCellEditorComponent(
      JTree tree, Object value, boolean isSelected, boolean expanded,
      boolean leaf, int row) {
    JLabel l = (JLabel) renderer.getTreeCellRendererComponent(
      tree, value, true, expanded, leaf, row, true);
    l.setFont(tree.getFont());
    setOpaque(false);
    if (value instanceof DefaultMutableTreeNode) {
      this.setEnabled(tree.isEnabled());
      this.setFont(tree.getFont());
      Object userObject = ((DefaultMutableTreeNode) value).getUserObject();
      if (userObject instanceof CheckBoxNode) {
        CheckBoxNode node = (CheckBoxNode) userObject;
        if (node.status == Status.INDETERMINATE) {
          setIcon(new IndeterminateIcon());
        } else {
          setIcon(null);
        }
        file = node.file;
        l.setIcon(fileSystemView.getSystemIcon(file));
        l.setText(fileSystemView.getSystemDisplayName(file));
        setSelected(node.status == Status.SELECTED);
      }
      // panel.add(this, BorderLayout.WEST);
      panel.add(l);
      return panel;
    }
    return l;
  }

  @Override public Object getCellEditorValue() {
    return new CheckBoxNode(file, isSelected() ? Status.SELECTED : Status.DESELECTED);
  }

  @Override public boolean isCellEditable(EventObject e) {
    if (e instanceof MouseEvent && e.getSource() instanceof JTree) {
      MouseEvent me = (MouseEvent) e;
      JTree tree = (JTree) e.getSource();
      TreePath path = tree.getPathForLocation(me.getX(), me.getY());
      Rectangle r = tree.getPathBounds(path);
      if (r == null) {
        return false;
      }
      Dimension d = getPreferredSize();
      r.setSize(new Dimension(d.width, r.height));
      if (r.contains(me.getX(), me.getY())) {
        // if (file == null && System.getProperty("java.version").startsWith("1.7.0")) {
        //   System.out.println("XXX: Java 7, only on first run\n" + getBounds());
        //   setBounds(new Rectangle(0, 0, d.width, r.height));
        // }
        return true;
      }
    }
    return false;
  }

  @Override public void updateUI() {
    super.updateUI();
    if (panel != null) {
      panel.updateUI();
    }
    // 1.6.0_24 bug??? @see 1.7.0 DefaultTreeCellRenderer#updateUI()
    renderer = new DefaultTreeCellRenderer();
  }
// ...