Popup menus were first introduced in AWT 1.1. These menus are not attached to a menubar; instead, they are free-floating menus that associate themselves with an underlying component. This component is called the invoker. Popup menus are brought into existence by a platform-dependent popup trigger event that occurs while the mouse is over the invoking component. In AWT and Swing, this trigger is typically a mouse event. Once raised, the user can interact with the menu normally. Figure 14.9 is an example of a popup menu in Swing.
Figure 14-9. A popup menu in Swing
You can add or insert
Action objects to
the popup menu by calling the
JPopupMenu class assigns an integer
index to each menu item and orders them based on the layout manager
of the popup menu. In addition, you can add separators to the menu by
method; these separators also count as
an index. Figure 14.10 shows the class diagram for
Figure 14-10. JPopupMenu class diagram
Popup menus are usually raised by invoking the
method in conjunction with the
platform-dependent popup trigger. The
method sets the
invoker properties of the popup before setting ...