Question

I’m developing a videogame in Android. For it, I’m using a game loop and all the typical stuff it envolves. I have a doubt about the states of the activity in android.

I need an activity to create the GLSurfaceView and so, the problem is the activity, when it finishes its onCreate method, continues this way: onCreate -> onResume -> onStart -> onStop.
I guess it goes throught those states because the activity doesn’t have anything to do and it’s the loop who is working. But I have a problem with this behaviour:

How can I know when the user “minimize” or put the device in a stand by state? Again, the methods onStop -> onResume -> onStart will trigger, but, how can I difference this time with the first?

I need to stop the loop when the user switch the device to stand by, but not when it starts the first time.

I hope I have explained well. Thanks.

Answer 1

If onStop is running immediately after onStart, something is wrong. The activity will only be placed in the Stopped state only when it is no longer visible to the user. Unless maybe your code immediately creates another activity that displaces it as the foreground activity, I guess, but if the activity is visible on the screen, onStop shouldn’t be firing. Some code would be helpful in diagnosing that.

onPause occurs when the activity is still visible but there is another activity that is being resumed. If you’re trying to save game data or something when the user backs out of the app, gets a phone call, turns off the screen, etc., I’d use onPause, because onStop is not guaranteed to be called and you run the risk in certain situations of the system killing your activity before you can do what you need to do.

For more info on activity lifecycle, see the Activities guide.