android memory management in activity lifecycle

Question

My question is a little bit complicated.

I want to understand how the app treats resources (especially images for backgrounds, buttons, etc.) when Activity is starte

Answer 1

Well before replying to your questions, I have certain facts to discuss.

1. As per the life cycle of the Activity, if we call finish() then the onStop() called and finally the onDestroy() which eligibles that Activity for Garbage Collection and remove from the Activity Stack of Android.

2. Android is maintaining the Drawable cache for the Activity designing and displaying on the screen. So if you disable the drawable cache on the Activity onCreate().

So the best practice is to disable drawable cache on the onCreate like this:

 LinearLayout v = (LinearLayout) findViewById(R.id.mainLayout);
        v.setDrawingCacheEnabled(false);

and to call finish(); on the onPause();