title: How to animate FloatingActionButton like in Google+ app for Android?
body: <p>I set FloatingActionButton to bottom of screen and I want to animate the button.</p>
  
  <ul>
  <li>Hidden when scrolling down</li>
  <li>Shown when scrolling up</li>
  </ul>
  
  <p>Like google implemented it in their <a href="https://play.google.com/store/apps/details?id=com.google.android.apps.plus" rel="noreferrer">Google+ app</a>.</p>
  
  <p>I think CoordinatorLayout and AppBarLayout is needed but how to implement it to use it with the FloatingActionButton?</p>