Android crash when app is closed and reopened

Question

I have a really simple android app that just displays a blank white screen. When I close the app by pressing the HOME button, then try to open the app again, it crashes and

Answer 1

Here is a simple solution which may be acceptable in some cases, like a background animation screen and activities which states do not need to be restored - the surface view activity needs to finish on pause.

protected void onPause()  { 
 super.onPause(); 
 finish();
} 

The better solution is to move the creation of the thread from the constructor into on surfaceCretaed like this:

@Override
public void surfaceCreated(SurfaceHolder holder) {
  _thread = new TutorialThread(holder, this);
  _thread.setRunning(true);
  _thread.start(); 
}

Then in the thread loop create a pause flag:

if(!pause){
  _panel.onDraw(c); 
}

finally in onPause and onRestore for the activity set the pause flag:

   protected void onResume() {
            super.onResume();
            pause = false;    
        }

        protected void onPause()  {   
            super.onPause();   
            pause = true;   
        } 

When the user clicks Home button surfaceDestroyed is invoked which will shut down the current thread "_thread". When he returns to the app, surfaceCreated will assign the reference "_thread" to a new thread, while the old thread object will be removed by the garbage collector.