title: How do I prevent the user from closing my app?
body: <p>I've an android application that will be used in a restaurant, so I want that users can't exit from the app.
  The only thing that users can, is using application.</p>
  <p>(If possible only admin can exit from app, by logging in or restarting device, I don't know which is the best way).</p>
  <p>Is there a solution or other way to do this?</p>