Weird “Receiver not registered” exception

Question

In onResume() I do:

registerReceiver(timeTickReceiver, new IntentFilter(Intent.ACTION_TIME_TICK));

and in onPause():

unregi         


        

Answer 1

A BroadcastReceiver should be registered in the onCreate() lifecycle method:

private BroadcastReceiver receiver;

@Overrride
public void onCreate(Bundle savedInstanceState){
    IntentFilter filter = new IntentFilter();

    receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            ...
        }
    }

    registerReceiver(receiver, filter);
}    

And a BroadcastReceiver should be unregistered in the onDestory() lifecycle method:

@Override
protected void onDestroy() {
    unregisterReceiver(receiver);
}

This will prevent the scenario of unregistering a BroadcastReceiver that has not yet been registered.

Answer 2

A broadcast receiver should be unregister in the onPause() lifecycle method

protected void onPause() {
    this.unregisterReceiver(reciever);
    super.onPause();
}

Answer 3

We've seen this error when doing a long press on a particular screen, and then immediately doing two orientation changes (e.g. turning the device upside down).

The API docs for unregisterReceiver says:

Unregister a previously registered BroadcastReceiver.

It doesn't say explicitly, but as you've seen, you hit IllegalArgumentException: Receiver not registered if it isn't already registered.

The workaround I'm using is to store my Receiver as a member field, and have it set to null whenever it is not registered, i.e. I initialize it to null, and then only set it when I register it. This might not be perfect, but it does solve my crashes!

private Receiver mReceiver = null;

From my onServiceConnected:

sLog.debug("Registering receiver");
mReceiver = new Receiver();
registerReceiver(mReceiver, filter);

From my onServiceDisconnected:

if (mReceiver == null)
{
  sLog.info("Do not unregister receiver as it was never registered");
}
else
{
  sLog.debug("Unregister receiver");
  unregisterReceiver(mReceiver);
  mReceiver = null;
}

Answer 4

I guess there may be some states where the receiver is not actually registered before e.g. a user exits the app.

You might want to try adding a check for the receiver before running unregister, (I've done this in several cases):

protected void onPause() {
  if(timeTickReceiver != null) {
    unregisterReceiver(timeTickReceiver);
  }
}

Answer 5

Easiest option would be to wrap try/catch block around the code.

try{
    ...
    this.unregisterReceiver(reciever);
   }
    catch(IllegalArgumentException e)
    {
        // TODO: handle exception
    }
    catch (Exception e) {
        // TODO: handle exception
    }