When Android kills an app, can a function be stopped halfway?

Question

I am wondering: when an app is to be killed, does Android wait for the currently running function to return, or does Android stop it before it ends by itself?

Answer 1

Updated: After testing, Android will kill any thread/AsynTask that is currently running(without calling onPostExecute()/onCancelled());

If you close Application normally. Your ui-thread stops, but If you implment your method in a Thread / AsyncTask / Service, it will continue to run until it finishes.
However, your Thread / AsyncTask may continue running but may or may not to be fully functional if you have a call back of your instance of the application or do something to the ui of the application. This MAY give you an Exception depending on what is being done.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                int i = 0;
                while (true) {
                    i++;
                    Thread.sleep(2000);
                    Log.i("not dead", "not dead" + i);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }).start();
}

Ran this code, and go play some games. Results were the thread will killed by the System.