如何将子菜单添加到MenuItem

Question

I'm trying to add submenu to a MenuItem which exists in a popup menu in system tray. Is there any way to achieve this? I've found some solutions about submenus but they use JMenuItem , and TrayIcon only accepts PopupMenu which only accepts MenuItem s.

Trying to achieve this with MenuItem :

Answer 1

A JMenuItem doesn't support submenus, you need to use another JMenu (add to you JPopupMenu ). See How to Use Menus for more details

For example...

JPopupMenu popupMenu = new JPopupMenu();

JMenu deviceMenu = new JMenu("Add Device");
deviceMenu.add(new JMenuItem("Add More..."));

popupMenu.add(deviceMenu);
popupMenu.add(new JMenuItem("Delete Device"));
popupMenu.add(new JMenuItem("Fire"));
popupMenu.add(new JMenuItem("Fault"));
popupMenu.add(new JMenuItem("Supress"));

(obviously, you'll still need to plugin functionality for all of this)

and TrayIcon only accepts PopupMenu which only accepts MenuItems.

There's a trick, you have to cheat a little, take a look at How do I get a PopupMenu to show up when I left-click on a TrayIcon in Java? for an example

Answer 2

Sure, you just add a Menu called "Add Device" to the PopupMenu ( Menu is a subclass of MenuItem , so it can be added).

PopupMenu popupMenu = new PopupMenu();
Menu subMenu = new Menu("Add Device");
subMenu.add(new MenuItem("Add More .."));
popupMenu.add(subMenu);