The JMenuBar Class
Swing’s JMenuBar class
supersedes the AWT MenuBar class.
This class creates a horizontal menu bar component with zero or more
menus attached to it. JMenuBar uses
the DefaultSingleSelectionModel as
its data model because the user can raise, or
activate , only one of its menus at a given time. Once the mouse
pointer leaves that menu, the class removes the menu from the screen (or
cancels it, in Swing lingo), and all menus again
become eligible to be raised. Figure 14-4 shows the class
hierarchy for the JMenuBar
component.

Figure 14-4. JMenuBar class diagram
You can add JMenu objects to
the menu bar with the add( )
method of the JMenuBar
class. JMenuBar then assigns an
integer index based on the order in which the menus were added. The menu
bar displays the menus from left to right on the bar according to their
assigned index. In theory, there is one exception: the help menu. You
are supposed to be allowed to mark one menu as the help menu; the
location of the help menu is up to the L&F. In practice, trying to
do this results in JMenuBar throwing
an Error.
Menu Bar Placement
You can attach menu bars to Swing frames or applets in one of two ways.
First, you can use the setJMenuBar(
) method of JFrame,
JDialog, JApplet, or JInternalFrame:
JFrame frame = new JFrame("Menu"); JMenuBar menuBar = new JMenuBar( ); // Attach the menu bar to the frame. frame.setJMenuBar(menuBar); ...