title: Android Asyntask: Use weak reference for context to avoid device rotate screen
body: <p>In <em><a href="http://www.apress.com/9781430239307" rel="noreferrer">Apress Pro Android 4</a></em> the author has said that: </p>
  
  <blockquote>
    <p>[...] context of currently running activity will no longer be valid when the device is rotated. [...] One approach is to use a weak reference to the activity instead of a hard reference [...]</p>
  </blockquote>
  
  <p>But the author just suggest this, and does not tell how it is done. Who has done this before please give me an example.</p>