if (propertyChangeListener == null) propertyChangeListener = new PropertyChangeHandler(); table.addPropertyChangeListener(propertyChangeListener);
  protected void installListeners()   {    if (focusListener == null)      focusListener = createFocusListener();    table.addFocusListener(focusListener);      if (keyListener == null)      keyListener = createKeyListener();    table.addKeyListener(keyListener);    if (mouseInputListener == null)      mouseInputListener = createMouseInputListener();    table.addMouseListener(mouseInputListener);        table.addMouseMotionListener(mouseInputListener);  }