Java Swing, 2nd Edition

Using Internal Frame Dialogs with JDesktopPane

In order to get the best results when using internal frame dialogs created by JOptionPane, the dialogs need to be placed in a JDesktopPane. However, this may not be convenient if your application does not use a JDesktopPane. In this section, we’ll show how you can easily adapt your application to use a JDesktopPane so that you can use internal frame dialogs.

Recall that JDesktopPane has a null layout manager, leaving the management of the location of its contents up to the DesktopManager and the user. This makes JDesktopPane a poor choice when you just need a container in which to build your main application. As a result, if you want to have an internal frame dialog displayed in a “normal” container, you need a solution that gives you the features of both JDesktopPane and a more layout-friendly container.

This is actually a pretty straightforward goal to achieve. You need to create a JDesktopPane and add your application container to it so that it fills an entire layer of the desktop. When there are no internal frames displayed, this looks the same as if you were displaying the application container alone. The benefit is that when you need to add an internal frame dialog, you have a desktop to add it to.

Here’s a simple example that shows how this works. It also shows how you can make sure your container fills the desktop, even if the desktop changes size (since there’s no layout manager, this won’t happen automatically).

// DialogDesktop.java ...