BroadcastReceiver Vs WakefulBroadcastReceiver

Question

Can somebody explain what the exact difference is between BroadcastReceiver and WakefulBroadcastReceiver?

In what situations would we have to use each Receiver class?

Answer 1

There is only one difference between BroadcastReceiver and WakefulBroadcastReceiver.

When you receive the broadcast inside onReceive() method,

Suppose,

BroadcastReceiver :

• It is not guaranteed that CPU will stay awake if you initiate some long running process. CPU may go immediately back to sleep.

WakefulBroadcastReceiver :

• It is guaranteed that CPU will stay awake until you fire completeWakefulIntent.

Example:

Here, when you receive broadcast, you are starting a service, as you are using WakefulBroadcastReceiver, it will hold wakelock and won't let the CPU sleep until you finish the work inside service and fire completeWakefulIntent

Code:

public class SimpleWakefulReceiver extends WakefulBroadcastReceiver {     @Override     public void onReceive(Context context, Intent intent) {         // This is the Intent to deliver to our service.         Intent service = new Intent(context, SimpleWakefulService.class);          // Start the service, keeping the device awake while it is launching.         Log.i("SimpleWakefulReceiver", "Starting service @ " + SystemClock.elapsedRealtime());         startWakefulService(context, service);     } }  class SimpleWakefulService extends IntentService {     public SimpleWakefulService() {         super("SimpleWakefulService");     }      @Override     protected void onHandleIntent(Intent intent) {         // At this point SimpleWakefulReceiver is still holding a wake lock         // for us.  We can do whatever we need to here and then tell it that         // it can release the wakelock.  This sample just does some slow work,         // but more complicated implementations could take their own wake         // lock here before releasing the receiver's.         //         // Note that when using this approach you should be aware that if your         // service gets killed and restarted while in the middle of such work         // (so the Intent gets re-delivered to perform the work again), it will         // at that point no longer be holding a wake lock since we are depending         // on SimpleWakefulReceiver to that for us.  If this is a concern, you can         // acquire a separate wake lock here.         for (int i=0; i<5; i++) {             Log.i("SimpleWakefulReceiver", "Running service " + (i+1)                     + "/5 @ " + SystemClock.elapsedRealtime());             try {                 Thread.sleep(5000);             } catch (InterruptedException e) {             }         }         Log.i("SimpleWakefulReceiver", "Completed service @ " + SystemClock.elapsedRealtime());         SimpleWakefulReceiver.completeWakefulIntent(intent);     } }