Swing I - Absolute Java - page 985

JMenu colorMenu = new JMenu("Add Colors");
JMenuItem blueChoice = new JMenuItem("Blue");
blueChoice.addActionListener( this );
colorMenu.add(blueChoice);
Note that, just as we did for buttons in Display 17.11, in Display 17.14 we registered
the this parameter as an action listener for each menu item. Defining action listeners
and registering listeners for menu items are done in the exact same way as for buttons.
In fact, the syntax is even the same. If you compare Displays 17.14 and 17.11, you will
see that the definition of the method actionPerformed is the same in both classes.
Add a JMenuItem to an object of the class JMenu using the method add in exactly
the same way that you add a component, such as a button, to a container object.
Moreover, if you look at the preceding code, you will see that you specify a string for a
JMenuItem in the same way that you specify a string to appear on a button.
A menu bar is a container for menus, typically placed near the top of a windowing
interface. Add a menu to a menu bar using the method add in the same way that you
add menu items to a menu. The following code from the constructor in Display 17.14
creates a new menu bar named bar and then adds the menu named colorMenu to this
menu bar:

in which they are added. The following code, taken from the constructor in Display 17.14,
creates a new JMenu object named colorMenu and then adds a JMenuItem labeled
"Red" . Other menu items are added in a similar way.

listeners

menu bar

JMenuBar bar = new JMenuBar();

bar.add(colorMenu);
There are two different ways to add a menu bar to a JFrame . You can use the method
setJMenuBar, as shown in the following code from the constructor in Display 17.14:

setJMenuBar(bar);
This sets an instance variable of type JMenuBar so that it names the menu bar named
bar. Saying it less formally, this adds the menu bar named bar to the JFrame and
places the menu bar at the top of the JFrame .
Alternatively, you can use the add method to add a menu bar to a JFrame (or to any
other container). You do so in the same way that you add any other component, such
as a label or a button. An example of using add to add a JMenuBar to a JFrame is given
in the file MenuAdd.java on the accompanying website.

extra code
on website

Menus

A menu is an object of the class JMenu . A choice on a menu is an object of the class
JMenuItem . Menus are collected together in a menu bar (or menu bars). A menu bar is an
object of the class JMenuBar .
Events and listeners for menu items are handled in exactly the same way as they are
for buttons.