Question

If I have an inner class that extends BroadcastReceiver within my Service class, should I care about synchronization, when the BroadcastReceiver class reads/writes to objects from the Service class?
Or to put it in another way: Are BroadacstReceiver‘s onReceive() Methods started in an extra thread?

Answer 1

The onReceive() method is always called on the main thread (which is also referred to as “UI thread”), unless you requested it to be scheduled on a different thread using the registerReceiver() variant:

Context.registerReceiver(BroadcastReceiver receiver,
                         IntentFilter filter,
                         String broadcastPermission,
                         Handler scheduler)