Swing/UndoManager のバックアップ(No.4)

private static void initUndoRedo(JTextComponent tc) {
  UndoManager manager = new UndoManager();
  tc.getDocument().addUndoableEditListener(manager);
  tc.getActionMap().put("undo", new UndoAction(manager));
  tc.getActionMap().put("redo", new RedoAction(manager));
  InputMap imap = tc.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
  imap.put(KeyStroke.getKeyStroke(KeyEvent.VK_Z, Event.CTRL_MASK), "undo");
  imap.put(KeyStroke.getKeyStroke(KeyEvent.VK_Y, Event.CTRL_MASK), "redo");
}
private static class UndoAction extends AbstractAction {
  private final UndoManager undoManager;
  public UndoAction(UndoManager manager) {
    super("undo");
    this.undoManager = manager;
  }
  @Override public void actionPerformed(ActionEvent e) {
    try{
      undoManager.undo();
    }catch(CannotUndoException cue) {
      //cue.printStackTrace();
      Toolkit.getDefaultToolkit().beep();
    }
  }
}