Update the UI of the calling activity or start a new activity when the alarm is triggered from a broadcast receiver

Question

I am writing an alarm code and using a broadcast receiver. I am able to receive the broadcast receiver. but now I want to come back to the calling activity and update the UI of my activity. I am not able to this. I used the following code in my activity but it is never executing that code.

 private BroadcastReceiver myBroadcastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "I am back!!", Toast.LENGTH_LONG).show();
    }
  };


  @Override
    protected void onPause()
    {
        super.onPause();
        unregisterReceiver(myBroadcastReceiver);
    }

    @Override
    protected void onResume()
    {
        super.onResume();
        IntentFilter intentFilter = new IntentFilter("com.test.Main");
        registerReceiver(myBroadcastReceiver, intentFilter);
    }

in the manifest file I have included the following, here gotAlarm is the broadcast receiver file

   <receiver android:name=".gotAlarm"
        android:enabled="true">
        </receiver>

gotAlarm file is one which gets called from the pending intent of the alarm set

public class gotAlarm extends BroadcastReceiver {
public void onReceive(Context context, Intent intent){
    Toast.makeText(context, "Wake Up!!", Toast.LENGTH_LONG).show();

   }
 }

May be I am missing something very basic. please help.

Answer 1

Two things:

1. If you dynamically register the receiver via Context.registerReceiver() then you won't receive broadcasts when Activity is paused (or stopped or not-running). If you need to receive broadcasts even when Activity is paused then create a top-level BroadcastReceiver class (as opposed to your inner class) and use <receiver> to register it.

2. BroadcastReceiver lifecycle docs state that BroadcastReceiver object is alive only during processing of onReceive() . You can not do any async tasks like showing dialogs, etc.. In your case (Activities might not be running and you receive a broadcast) you should use NotificationManager to notify user something happened.

Answer 2

I have dropped this way and I am starting a new activity on receiving broadcast. And I am sending information data from calling activity to broadcast and from broadcast to next activity. This has served the purpose.

Answer 3

Did you register your BroadcastReceiver (you can do this in the 'onResume'-method of your Activity)? Also, you should unregister your BroadcastReceiver in the 'onPause'-method.