Question

I can successfully call activity.onPause() to pause the application.
But when i call activity.onResume() the application restarts.

Is there a way to avoid this ?

Edited

I actually want to pause my application using a pause button

Answer 1

You should never call methods of the Activity life cycle by yourself! So no call to onPause() onResume() onDestroy() onCreate() onStop() or onStart().

Edit to fit your edited question:

You should pause your game, not the Activity. You must have a thread where you work your game logic. That thread needs to be paused, not the game. So consider working on a pause logic there.