Core JFC Java Foundation Classes 2nd edition - Read

Not used
}
public void menuCanceled(MenuEvent evt) {
// Not used
}
});
You can try this code using the command:
j ava JFCBook.Chapter6.MenuExample6
The Menu Bar and the Menu System 649
When you click on the File menu, a MenuEvent will be posted from the
JMenu object just before the menu is made visible. When this event is passed
to the listener's menuSelected method, the state of all of its menu items is
adjusted based on the application s internal state. Therefore, the menu items'
state will be correct when the menu is displayed, but may be out-of-date
when it is not. This doesn't matter, of course, because the user can't see that
the menu items are in the wrong state.
As a consequence of implementing the MenuListener, all of the code
that enables and disables menu items that were introduced in the previous
section can be removed. Using a MenuListener is obviously cleaner—the
code is all in one place and it is much more easily understandable. We recommend
using this technique whenever possible.
Using Actions with Menus
So far in this chapter, all of the menu items have been created directly and
ActionListeners have been added to them to handle the event generated
when they are selected. In the last chapter, you saw how useful the concept
of an Action was when handling events from the keyboard, since Actions
make it possible to combine an ActionListener with some state information
needed when the action is to be performed. A useful feature of the
JMenu class is that it allows you to add an Action directly to a menu:
public JMenuItem add(Action action);
In order for this to work properly, you have to create an Action with an
appropriate text string, which is then used as the label of the menu item. For
example, you can use the AbstractAction class to create a suitable
Action. Here's how you might add an Action to process the Save operation:
JMenu menu = new JMenu("File");