How to prevent the screen of an android device to turn off during the execution of an Activity?

Question

I have an Activity that usually needs some time to watch the screen without interacting with it.

The problem is that the screen turns off, just like wit

Answer 1

To change it on-the-fly do this:

if (keepScreenOn)
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
else
    getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);