Broadcast Receiver: Two ways to implement part-2

In the previous tutorial, we discussed how to implement/register broadcast receiver inside an activity. Broadcast receiver is a standalone application component which means it will continue running even when other application component are not running. That's why we unregister broadcast receiver in onPause on the activity.

Second way of using broadcast receiver is to register it inside manifest.xml. When registered (and not unregistered) broadcast receiver exists as long as application exists. There could be many use cases of using broadcast receiver this way. These could be waiting for specific event to occur and start/stop other application component upon the occurrence of that event, initiate network communication or communicate with contentprovider . . .etc.

This is pretty simple to implement. We need to register it using receiver tag in manifest.xml and define its intent-filter (same as we did in activity).

<receiver
      android:name=".IndependentReceiver"  >
     <intent-filter>
         <action android:name="sohail.aziz.r2" />
      </intent-filter>
 </receiver>

Lets define the broadcast receiver itself:

public class IndependentReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        
        int recval = intent.getIntExtra("counter", 0);
        Log.d("sohail", "independentreceiver: broadcast received with counter="+recval);
        
    }

}

Now we can send broadcast to this receiver with action sohail.aziz.r2  e.g
  

  Intent in = new Intent();
  in.setAction("sohail.aziz.r2");
  in.putExtra("counter", 202);
  Log.d("sohail", "onHandleIntent: sending broadcast");
  sendBroadcast(in);

Notice that as we are not unregistered this receiver, so it will continue running throughout the application life.
Browse and Download source BroadcastExample.

Broadcast Receiver: Two ways to implement part-1

I got confused while learning about the broadcast receiver after browsing around the web. Some people register it inside activities while other register it in manifest. The purpose of this tutorial is to explain both ways and the use-cases when to use which implementation.

Broadcast receiver is an application component like activity and service. Its sole aim is to listen for broadcast for which it is registered (through intent-filters). Broadcast receiver can receive broadcast from android system, other applications and from inside the application. Read more about broadcast receivers at developer.android.

We can register receiver in manifest.xml or inside an Activity. We should use define and register broadcast receiver inside activity if we want perform action related to activity (e.g updating UI). We should define it in standalone class otherwise.

No matter what your use-case is, Lets see how to implement these two ways. Lets say we have BroadcastExampleActivity and a receiver inside it called Myreceiver:

public class BroadcastExampleActivity extends Activity {
    /** Called when the activity is first created. */
    private Myreceiver reMyreceive;
    private IntentFilter filter;
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        unregisterReceiver(reMyreceive);
     }
     @Override
     protected void onResume() {
        // TODO Auto-generated method stub
         super.onResume();
        
          registerReceiver(reMyreceive, filter);
     } 

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        Log.d("sohail", "onCreate called");
       
        reMyreceive=new Myreceiver();
       
       //typo mistake 
       //Edited after pointing out by a reader, thanks 
       // IntentFilter filter=new IntentFilter("sohail.aziz");

        filter=new IntentFilter("sohail.aziz");         
       
        Intent i= new Intent(this,MyIntentService.class);
        Log.d("sohail", "starting MyIntentservice");
        startService(i);
    }
    
    public class Myreceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            // TODO Auto-generated method stub
            
            Log.d("sohail", "MyReceiver: broadcast received");
        }
        
    }
} 

Note that while implementing inside activity, receiver should be registered in OnResume() and unregistered in OnPause() in order to "cut down unnecessary system overhead- developer.android". [Otherwise your receiver will continue running even when activity get paused! check example in updated source]. Intenfilter("sohail.aziz") is the action name for which this receiver is listening. Broadcast sender must set the action name for intended recipient. Lets define MyIntentservice which will send the broadcast.

public class MyIntentService extends IntentService{

    public MyIntentService() {
        super("MyIntentService");
        // TODO Auto-generated constructor stub
        
        Log.d("sohail","Myintentservice constructor");
    }

    @Override
    protected void onHandleIntent(Intent arg0) {
        // TODO Auto-generated method stub
        
        Log.d("sohail", "onHandle intent called");
        
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        Intent in= new Intent();
        in.setAction("sohail.aziz");
        Log.d("sohail", "onHandleIntent: sending broadcast");
        sendBroadcast(in);
     
    
    }

}

Notice that we are sending broadcast here with action "sohail.aziz", this is the same action name for which we set intentfilter in our broadcast receiver. Now when broadcast is sent by sendBroadcast, Myreceiver onReceive will be called and intent will be passed to it. You can pass anything via intent. This way we don't need to register receiver inside manifest.xml as it has become a sub component of the activity.

Second method: Broadcast Receiver: Two ways to implement part-2