Learning Java by Building Android Games - Second Edition

The game loop

What is a game loop anyway? Almost every game has a game loop. Even games you might suspect do not, like turn-based games, still need to synchronize player input with drawing and AI while following the rules of the underlying operating system.

There is a constant need to update the objects in the game, perhaps by moving them, draw everything in its current position all the while responding to user input. A picture might help:

Our game loop comprises three main phases.

1. Update all game objects by moving them, detecting collisions and processing AI (artificial intelligence) if used
2. Based on the just-updated data, draw the frame of animation ...