title: call activity method from inner viewpager fragments
body: <p>I'm working on an android app and I've got a viewPager with 4 fragments.
  In each fragment there are some input views.</p>
  
  <p>Is it possible to declare a method in the activity that read each input view values, called on each input views status change?</p>
  
  <p>Thank you </p>
  
  <p>Alessandro</p>