JComboBoxにJSeparatorを挿入

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Summary

JComboBoxに選択できないJSeparatorを挿入します。

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Source Code Examples

JComboBox<Object> combo = new JComboBox<>();
combo.setRenderer(new DefaultListCellRenderer() {
  @Override public Component getListCellRendererComponent(
      JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
    if (value instanceof JSeparator) {
      return (Component) value;
    } else {
      return super.getListCellRendererComponent(
          list, value, index, isSelected, cellHasFocus);
    }
  }
});
DefaultComboBoxModel model = new DefaultComboBoxModel() {
  @Override public void setSelectedItem(Object o) {
    if (o instanceof JSeparator) {
      return;
    }
    super.setSelectedItem(o);
  }
};
model.addElement("aaaaa");
model.addElement(new JSeparator());
model.addElement("bbbbb");
combo.setModel(model);
View in GitHub: Java, Kotlin

Description

  • ListCellRenderer
    • JSeparatorが選択された場合は、セル描画ComponentとしてJSeparatorを返すListCellRendererを設定
  • DefaultComboBoxModel
    • JSeparatorが選択された場合は何もしないよう、setSelectedItemメソッドをオーバーライド
  • DefaultComboBoxModel#setSelectedItemメソッドをオーバーライドする代わりに、以下のようにJSeparatorが選択された場合はひとつ前のItemに戻すようなItemListenerを追加しても同様 
    combobox.addItemListener(new ItemListener() {
  private Object prev;
  @Override public void itemStateChanged(ItemEvent e) {
    if (e.getStateChange() == ItemEvent.SELECTED) {
      Object obj = e.getItem();
      if (obj instanceof JSeparator) {
        if (prev == null) {
          prev = combobox.getItemAt(0);
        }
        combobox.setSelectedItem(prev);
      } else {
        prev = obj;
      }
    }
  }
});
  • UpDownキーでの選択状態移動を可能にする(JSeparatorなら飛ばす)場合は、以下のようなキーストロークのアクションを設定する必要がある 
    Action up = new AbstractAction() {
  @Override public void actionPerformed(ActionEvent e) {
    int index = combobox.getSelectedIndex();
    if (index == 0) {
      return;
    }
    Object o = combobox.getItemAt(index - 1);
    if (o instanceof JSeparator) {
      combobox.setSelectedIndex(index - 2);
    } else {
      combobox.setSelectedIndex(index - 1);
    }
  }
};
Action down = new AbstractAction() {
  @Override public void actionPerformed(ActionEvent e) {
    int index = combobox.getSelectedIndex();
    if (index == combobox.getItemCount() - 1) {
      return;
    }
    Object o = combobox.getItemAt(index + 1);
    if (o instanceof JSeparator) {
      combobox.setSelectedIndex(index + 2);
    } else {
      combobox.setSelectedIndex(index + 1);
    }
  }
};
ActionMap am = combobox.getActionMap();
am.put("selectPrevious3", up);
am.put("selectNext3", down);
InputMap im = combobox.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "selectPrevious3");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_KP_UP, 0), "selectPrevious3");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "selectNext3");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_KP_DOWN, 0), "selectNext3");

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