activity diagram multiple choices code example

Example: same activity called multiple times

Android will recreate your activity after certain "device configuration changes". One such example is orientation. You can read more here... http://developer.android.com/guide/topics/resources/runtime-changes.html

Perhaps something in your threads is doing something which is considered a configuration change?

If that's the case you might find it useful to extend the Application class instead and do your initialization there. See this post... Activity restart on rotation Android