java - 菜单项回调不起作用

Question

//当我点击"file"时，以下回调起作用

    menuBar = new JMenuBar();
    frame.setJMenuBar(menuBar);

    mnFile = new JMenu("File");
    mnFile.addMouseListener(new MouseAdapter() {
        @Override
        public void mouseClicked(MouseEvent e) {
            btnNewButton_0.setText("File pressed");
        }
    });
    menuBar.add(mnFile);

//点击菜单项:open时以下回调未能响应

    mntmOpen = new JMenuItem("Open");
    mntmOpen.addMouseListener(new MouseAdapter() {
        @Override
        public void mouseClicked(MouseEvent e) {
            btnNewButton_0.setText("Open pressed");
        }
    });
    mnFile.add(mntmOpen);

//不确定我错过了什么？

Answer 1

不要使用 MouseListener!!!

如果您想在单击 JMenu 时执行某些操作，请使用 JPopupMenuListener:

JMenu file = new JMenu( "File" );

JPopupMenu popup = file.getPopupMenu();
popup.addPopupMenuListener(new PopupMenuListener()
{
    public void popupMenuCanceled(PopupMenuEvent e) {}

    public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {}

    public void popupMenuWillBecomeVisible(PopupMenuEvent e)
    {
        System.out.println("menu clicked");
    }
});

否则，只需将 ActionListener 添加到 JMenuItem 即可，如 How to Use Menus 上的 Swing 教程中所示。 .