Reviews : Unfreeze Your Applications with the New SwingWorker :

Unfreeze Your Applications with the New SwingWorker

by Dan Andrews

Poorly-written Swing applications can appear to freeze when time-consuming code is executing. These applications frequently fail to provide their users with feedback on the code's execution state. In the worst case, end users will wonder if the application is working correctly.

This unresponsiveness happens because all Swing applications handle events on the event dispatch thread. This means painting, layout updates, button presses, rollover effects, and Swing component interactions. When this kind of time-consuming code is executed on the event dispatch thread, all other-event driven activity waits and the application appears frozen.

A Possible Solution

The code in Listing 1 is not complex, but it is error prone. You might type thread.run() instead of thread.start(). In that case, your application would continue to exhibit the frozen behavior—and possibly other unexpected behaviors. Typing thread.run() in this case would be an easy error to detect, but only because it is a serious error to use invokeAndWait on the event dispatch thread. So this solution isn't really all that effective. Additionally, the code in Listing 1 is several lines long and there is no way to easily reuse it.

A Reusable Solution

On December 11, 2006, the Java SE 6 platform was officially released and with it, a complete rewrite of the javax.swing.SwingWorker became available to Java developers. Including the SwingWorker in a JDK has been a huge improvement. You can now refer to the SwingWorker class and everyone can be sure the reference is to the javax.swing.SwingWorker. Hopefully, usage examples of the SwingWorker in Java SE 6 platform will begin to be more consistent and familiar to programmers and its usage will increase.

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