Question

I have an Android application which uses C2DM services (aka push).

I have a separate class which implements the registration process and which receives the data (and extends BroadcastReceiver).

I want to communicate this data to the activity which currently is in the foreground. The activity currently in the foreground may differ depending on user action.

What’s the best way to communicate in between the receiver and the current activity?

Thanks.

Answer 1

I solved this problem by sending out a new broadcast from the C2DMReceiver class, which looked something like this.

The C2DMReceiver class:

public class C2DMReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals("com.google.android.c2dm.intent.REGISTRATION")) {    
            handleRegistration(context, intent);
        } else if (intent.getAction().equals("com.google.android.c2dm.intent.RECEIVE")) {
            handleMessage(context, intent);
        }
    }

    private void handleRegistration(Context context, Intent intent) {
        // handle registration
    }

    private void handleMessage(Context context, Intent intent) {
        Intent i = new Intent("push");
        i.putExtras(intent);
        // context.sendOrderedBroadcast(i, null);
        context.sendBroadcast(i);
    }

}

Another class I called PushReceiver. This is the class that will extend BroadcastReceiver and receive the broadcast sent by C2DMReceiver.

public class PushReceiver extends BroadcastReceiver {

    public PushReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        // do stuff
        abortBroadcast();
    }

    public static class PushFilter extends IntentFilter {

        private static final int DEFAULT_PUSH_PRIORITY = 1;

        public PushFilter() {
            this(DEFAULT_PUSH_PRIORITY);
        }

        public PushFilter(int priority) {
            super("push");
            setPriority(priority);
        }

    }

}

And the activity class, in this case called MyActivity. This should work well if you are using a base activity class that all other activities extend. That way every activity registers the receiver. By doing the register/unregister in onResume/onPause, you should be able to guarantee that only the current activity receives the broadcast. If not, you can send an ordered broadcast from C2DMReceiver and use priority in the PushFilter.

public class MyActivity extends Activity {

    private PushReceiver pushReceiver;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // your onCreate method
        pushReceiver = new PushReceiver();
    }

    public void onResume() {
    super.onResume();
        // your onResume method
        registerReceiver(pushReceiver, new PushReceiver.PushFilter());
    }

    public void onPause() {
        super.onPause();
        // your onPause method
        unregisterReceiver(pushReceiver);
    }

}    

In my case, I wrote the PushReceiver constructor to take a View and then “did stuff” with the view in the onReceive method. Without knowing more about what your trying to do, I can’t elaborate on this, but hopefully this can provide a decent template to work from.