Flashing Screen or Blinking Screen in Android

please may you tell me how i can turn off back light of android device, i try through the setBrightness method but it not works on emulator

my main task is to develop an android application in which whenever any event is occurs then a system have 开发者_JAVA技巧to alert the user by such an alarm in which some mp3 file is playing and flashing screen or blinking screen is showing.

I do the Mp3 file playing task, but how I can do for the Blinking Screen.

I use the Services, not in activity, so cant use the WindowManager, so please there is any way to do this by helping methods which call through Service instead of Activity.

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Emulator does not support brightness changing. For example, if you go to phone settings and change brightness there, nothing will happen. You need a real device if you want to see brightness changes.