问题
I'm writing a small app where I don't want the current activity to automatically switch to the phonecall app upon an incoming call. I would like the user to decide whether to do it or not from my app UI.
I know I can listen to state changes in the telephony but I don't know how to prevent from the phonecall app to take focus.
来源：https://stackoverflow.com/questions/5744720/how-to-let-android-user-to-decide-whether-to-answer-a-call-or-not