Prohibit Screenshot in your android App.

If you want to stop screenshot in all screen of your app then you need to create a BaseActivity and extend this activity to all your activity in which you want to stop screenshot.
Add below mentioned line in onCreate method of BaseActivity.
--------------------------- OR -----------------------------
If you want to prohibit screenshot in particular screen then add below mentioned line if specific activity.

getWindow().setFlags(WindowManager.LayoutParams.FLAG_SECURE, 
WindowManager.LayoutParams.FLAG_SECURE);