Java Swing

Beyond Buttons

Buttons are very useful, but even with great images forming the buttons, they still lack a certain glamour—every application has buttons. For the next example, let’s take a look at something a bit more exciting. (Well, exciting might be a bit of an exaggeration, but it definitely has more impact than buttons.) The Swing package contains a new class called JInternalFrame , which allows you to create free-standing frames with menus, titlebars, and everything else a Frame needs right inside your application.

What Is an Internal Frame?

Before we start coding, here’s a brief rundown of the features of an internal frame:

• Same functions as a normal Frame object, but confined to the visible area of the container it is placed in

• Can be iconified (icon stays inside main application frame)

• Can be maximized (frame consumes entire main application frame area)

• Can be closed using the standard controls for popup windows

• Can be placed in a “layer,” which dictates how the frame displays itself relative to other internal frames (a frame in layer 1 can never hide a frame in layer 2)

Figure 2.6 shows a simple internal frame using the Metal L&F.

Figure 2-6. The SimpleInternalFrame application using the Metal look-and-feel

For this first example, we’ll add an empty internal frame to an application. Once that’s working, we’ll expand the simple frame to create a couple of different types of internal ...