In an Android 2D game which is using SurfaceView where its onDraw is driven by a loop from a Thread, I use many bitmap sprites (sprite sheets) and two background size bitmaps, which are all loaded into memory at the start.
It all works fine, however, when the activity is onPause or after reloading it few times, Android shows a tendency to wipe out the big bitmaps only, probably to free memory. Sometimes this happens even in the middle of loading this very activity.
In order to counter this, I made a check in the onDraw method to test if the big bitmaps are still there and reload them if they are forcefully recycled by Android, before drawing them on Canvas.
This solution may not be the most stable, and since I know that there are much more accomplished android game programmers here than myself, I hope you can reveal some tricks or secrets or at least provide some good hints, how to overcome this.