Swing/DefaultEditorKit のバックアップ(No.20)

//textField.setComponentPopupMenu(new TextFieldPopupMenu());
class TextFieldPopupMenu extends JPopupMenu {
  private final Action cutAction = new DefaultEditorKit.CutAction();
  private final Action copyAction = new DefaultEditorKit.CopyAction();
  private final Action pasteAction = new DefaultEditorKit.PasteAction();
  private final Action deleteAction = new AbstractAction("delete") {
    @Override public void actionPerformed(ActionEvent e) {
      Component c = getInvoker();
      if (c instanceof JTextComponent) {
        ((JTextComponent) c).replaceSelection(null);
      }
    }
  };
  private final Action cut2Action = new AbstractAction("cut2") {
    @Override public void actionPerformed(ActionEvent e) {
      Component c = getInvoker();
      if (c instanceof JTextComponent) {
        ((JTextComponent) c).cut();
      }
    }
  };
  protected TextFieldPopupMenu() {
    super();
    add(cutAction);
    add(copyAction);
    add(pasteAction);
    add(deleteAction);
    addSeparator();
    add(cut2Action);
  }
  @Override public void show(Component c, int x, int y) {
    if (c instanceof JTextComponent) {
      JTextComponent tc = (JTextComponent) c;
      boolean f =  tc.getSelectionStart() != tc.getSelectionEnd();
      cutAction.setEnabled(f);
      copyAction.setEnabled(f);
      deleteAction.setEnabled(f);
      cut2Action.setEnabled(f);
      super.show(c, x, y);
    }
  }
}