Summary

GUI frameworks are nearly always implemented as single-threaded subsystems in which all presentation-related code runs as tasks in an event thread. Because there is only a single event thread, long-running tasks can compromise responsiveness and so should be executed in background threads. Helper classes like SwingWorker or the BackgroundTask class built here, which provide support for cancellation, progress indication, and completion indication, can simplify the development of long-running tasks that have both GUI and non-GUI components.