This was probably the most technical chapter so far. Threads, game loops, timing try and catch blocks, using interfaces, the Activity lifecycle, etc… It's an awfully long list of topics to cram into 35 pages. If the exact interrelationships between these things are not entirely clear it is not a problem. All you need to know is that when the player starts and stops the game the PongActivity class will handle starting and stopping the thread by calling the PongGame class' pause and resume methods. It achieves this via the overridden onPause and onResume methods which are called by the OS.

Once the thread is running the code inside the run method executes alongside the UI thread that is listening for player input. As we call the update and draw methods from the run method at the same time as keeping track of how long each frame is taking, our game is ready to rock and roll. We just need to add some game objects to update in each call to update and draw in each call to draw.

In the next chapter, we will be coding, updating and drawing both the bat and the ball classes.