Dynamic BroadcastReceivers: LocalBroadcastManager.registerReceiver vs registerReceiver

Question

I'm trying to receive broadcasts from a service with 2 different receivers. One receiver update's a view so I register it in the activity's onResume method.

When the app is not in the foreground I use the other receiver so I can show a system notification when the background service completes.

The code below is how I'm registering my receivers:

@Override
protected void onPause() {
    // unregister local
    unregisterReceiver(localReceiver);

    // register remote
    registerReceiver(remoteReceiver, filter);
    super.onPause();
}

@Override
protected void onResume() {
    super.onResume();
    // remove remote receiver
    // since remote is only registered in onPause it won't be registered during the first onResume call
    // so we want to ignore any exceptions
    try {
        unregisterReceiver(remoteReceiver);
    } catch (IllegalArgumentException e) {
        Log.e(LOG_TAG, "No receiver registered, could be first time");
    }

    // add local receiver
    registerReceiver(localReceiver, filter);
    Log.i(LOG_TAG, "resumed. should be registered");
}

The two receiver's are instantiated like this at the top of the Activity class:

BroadcastReceiver localReceiver = new BroadcastReceiver() { ... };

WaitTimeReceiver remoteReceiver = new WaitTimeReceiver();

The Service makes the intent as:

broadcastIntent = new Intent(Support.SERVICE_BR);
broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);

// later on sends using
sendBroadcast(broadcastIntent);

The Filter in the Activity is made to match:

filter.addAction(Support.SERVICE_BR);
filter.addCategory(Intent.CATEGORY_DEFAULT);

Everything above is working the pause resume functionality works as expected, but my question is why the LocalBroadcastManager was not?

Using LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this) and then calling lbm.registerReceiver(localReceiver) was not receiving any of my broadcasts for either.

Why wasn't the LocalBroadcastManager receiving any of my broadcasts?

Answer 1

BroadcastReceivers registered with LocalBroadcastManager can only receive broadcasts sent with LocalBroadcastManager. Broadcasts sent with an Activity's or Service's sendBroadcast() method cannot be received by LocalBroadcastManager Receivers.

Use the LocalBroadcastManager#sendBroadcast() method instead. For example:

LocalBroadcastManager.getInstance(this).sendBroadcast(intent)