Start and Stop Behavior

There are cases where a bundle either does not have any imported services, or wishes to execute behavior that does not depend upon its imported services. Since SAT makes the BundleActivator methods start(BundleContext) and stop(BundleContext) final, the methods start() and stop() are provided for this purpose. For example, a bundle that wishes to open a window when it starts and close the window when it stops could implement the following methods:

   protected void start() {
     ClientFeatureAdminWindow window = getWindow();
     window.open();
   }

   protected void stop() {
     ClientFeatureAdminWindow window = getWindow();
     window.close();
   }

The method start() is always called exactly once when the bundle is started. The method activate(), on the other hand, is called whenever all the bundle's imported services have been acquired. While the start() method is only called once, the activate() method can be called multiple times.
The method stop() is always called exactly once when the bundle is stopped. The method deactivate(), on the other hand, is called whenever the bundle no longer has acquired all of its imported services. While the stop() method is only called once, the deactivate() method can be called multiple times.