I've followed the followin tutorial to develop a push notification messaging app in android:
http://quickblox.com/developers/SimpleSample-messages_users-android#Setup_GCM
By now, I am able to send push notifications to myself successfully. But suppose, I want to send push notification to my friend having the same app, then I'll need his App ID. So my only question is, how can I find his App ID programatically (without going to the website manually and taking it down)
Got the issue solved. Actually the problem itself solved the issue on its own, i.e. whenever I sent notification to myself it worked, however, if the same app is run from another from and the notification is sent, then along with that device the notification is sent to me as well. So, I came to know that the notification will be sent to each device, the app is registered (All are provided with same App ID on registering with GCM) and I can send the notification to desired person using their mobile number while just hiding the code for notification display for push message for other mobile numbers!!!