java - 如何在JComboBox中显示自定义PopupMenu

Question

JComboBox 单击时显示列表。我想显示一个 JPopupMenu 而不是列表。 在以下代码中，事件被触发，但弹出窗口未显示。为什么？

JComboBox box = new JComboBox();

box.addPopupMenuListener(new PopupMenuListener() {
   @Override
   public void popupMenuWillBecomeVisible(PopupMenuEvent e) {      
     popupMenu.show(box, 0, box.getHeight());
   }
   ...
});

Answer 1

或者可以使用 mouseListener。由于 JDK 错误 https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4144505 必须将 mouseListener 添加到所有后代，如下所示:

 MouseAdapter comboPopupAdapter = new MouseAdapter() {
      @Override
      public void mousePressed(MouseEvent e) {
        popupMenu.show(box, 0, box.getHeight());
      }
    };
    box.addMouseListener(comboPopupAdapter);
    for (Component c : box.getComponents()) {
      c.addMouseListener(comboPopupAdapter);
    }