title: How to set onBackButton listener to an activity
body: <p>I have a Class A which runs activity via <code>startActivityForResult</code> by passing <code>Intent</code> to it. In other class, lets say B I get this <code>Intent</code> and recreate activity by it. How can I listen events for that activity, e.g. activity which was started for result is running and user pressed "back" button so I want to do some action.
  How can I do this?
  Thank you on advance.</p>
  
  <p>Activity in which i recreate instance of object is not derived from Activity class. It is just ACTIVITY. So I have only object. is there any way to do such stuff with instance of class but not a class?</p>