Swing/DeleteKeyBeep のバックアップ(No.2)

String key = "delete-previous";
final Action deletePreviousAction = am.get(key);
am.put(key, new TextAction(DefaultEditorKit.deletePrevCharAction) {
  //@see javax/swing/text/DefaultEditorKit.java DeletePrevCharAction
  @Override public void actionPerformed(ActionEvent e) {
    JTextComponent target = getTextComponent(e);
    if(target != null && target.isEditable()) {
      Caret caret = target.getCaret();
      int dot = caret.getDot();
      int mark = caret.getMark();
      if(dot==0 && mark==0) {
        return;
      }
    }
    deletePreviousAction.actionPerformed(e);
  }
});
key = "delete-next";
final Action deleteNextAction = am.get(key);
am.put(key, new TextAction(DefaultEditorKit.deleteNextCharAction) {
  //@see javax/swing/text/DefaultEditorKit.java DeleteNextCharAction
  @Override public void actionPerformed(ActionEvent e) {
    JTextComponent target = getTextComponent(e);
    if(target != null && target.isEditable()) {
      Document doc = target.getDocument();
      Caret caret = target.getCaret();
      int dot = caret.getDot();
      int mark = caret.getMark();
      if(dot==mark && doc.getLength()==0 || doc.getLength()==dot) {
        return;
      }
    }
    deleteNextAction.actionPerformed(e);
  }
});