title: onAttach callback from fragment to activity
body: <p>I want to send <code>String</code> data from <code>fragment</code> to <code>activity</code>. </p>
  
  <p>I have read the article about communicating between fragment and activity in android developer, using <code>onAttach</code> callback.</p>
  
  <p>can anyone explain clearly how to send data from fragment to activity?</p>