The Java™ Tutorials
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Worker Threads and SwingWorker
Trail: Creating a GUI With Swing
Lesson: Concurrency in Swing

Worker Threads and SwingWorker

When a Swing program needs to execute a long-running task, it usually uses one of the worker threads, also known as the background threads. Each task running on a worker thread is represented by an instance of javax.swing.SwingWorker. SwingWorker itself is an abstract class; you must define a subclass in order to create a SwingWorker object; anonymous inner classes are often useful for creating very simple SwingWorker objects.

SwingWorker provides a number of communication and control features:

These features are discussed in the following subsections.


The javax.swing.SwingWorker class was added to the Java platform in Java SE 6. Prior to this, another class, also called SwingWorker, was widely used for some of the same purposes. The old SwingWorker was not part of the Java platform specification, and was not provided as part of the JDK.

The new javax.swing.SwingWorker is a completely new class. Its functionality is not a strict superset of the old SwingWorker. Methods in the two classes that have the same function do not have the same names. Also, instances of the old SwingWorker class were reusable, while a new instance of javax.swing.SwingWorker is needed for each new background task.

Throughout the Java Tutorials, any mention of SwingWorker now refers to javax.swing.SwingWorker.

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