Android: How to turn screen on and off programmatically?

Question

Before marking this post as a \"duplicate\", I am writing this post because no other post holds the solution to the problem.

I am trying to turn off the device, then

Answer 1

As per Android API 28 and above you need to do the following to turn on the screen

setShowWhenLocked(true); 
setTurnScreenOn(true); 
KeyguardManager keyguardManager = (KeyguardManager)
getSystemService(Context.KEYGUARD_SERVICE);
keyguardManager.requestDismissKeyguard(this, null);