Waiting and Blocking Input

Those pesky users are always trying to submit forms more than once, or creating new files willy nilly while they're waiting for feedback.

This article addresses two strategies for avoiding Impatient User Syndrome. First, provide some feedback to show that the program is busy, and second, don't allow any additional input.

Now, Java provides a JProgressBar, which you can throw up in a Dialog, but those aren't always appropriate. Sure if you want to block all application input (or in the case of Java 1.6, all frame input), that'll work, and you can always disable one component at a time. But suppose, for instance, that you've got a single frame, with a couple of different sections or docked panels. If their operation is independent of one another, you certainly don't want to block them all with a dialog.

The following demo shows how to block input on individual components, groups of components, or an entire frame, as well as providing "busy" feedback. The class WaitIndicator installs a component in the JLayeredPane above the target component, which prevents any mouse input from reaching the target component, and displays an hourglass cursor over the target component. It also installs a key event handler to ensure that no key events reach the target component.

The WaitIndicator also provides a paint method, which you can use to provide whatever visual feedback is appropriate to your program. The default implementation fades to the target component's background color. The demo itself uses a SpinningDialWaitIndicator, which paints an Apple-like spinner (which you can also see in the animated icon demo applet a few entries back).





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