Monitoring Progress
By themselves, progress bars are pretty boring. Swing,
however, combines progress bars with the dialog capabilities of JOptionPane to create the ProgressMonitor and ProgressMonitorInputStream classes. You can
use ProgressMonitor to report on the
current progress of a potentially long task. You can use ProgressMonitorInputStream to automatically
monitor the amount of data that has been read in with an InputStream. With both, you can define various
strings to be posted in the progress monitor dialogs to offer a better
explanation of the task at hand.
The ProgressMonitor Class
The ProgressMonitor
class is a generic progress dialog box that can be used
for practically anything. There are two string descriptions that can
be set on a ProgressMonitor dialog
box. The first is a static component that can never change; it appears
on the top of the dialog and is set in the constructor. The second is
a variable string-based property that can be reset at any time. It
appears below the static string, slightly above the progress bar.
Figure 6-15 shows the
structure for this class.

Figure 6-15. ProgressMonitor class diagram
Once instantiated, the ProgressMonitor dialog (shown in Figure 6-16) does not pop up immediately. The dialog waits a configurable amount of time before deciding whether the task at hand is long enough to warrant the dialog. If it is, the dialog is displayed. When ...