title: Android animate toolbar icon while changing its image
body: <p>in my app i need to change the image of a toolbar button programmatically, and for so I´m using:</p>
  
  <pre><code>public boolean onCreateOptionsMenu( Menu menu ) {
          getMenuInflater().inflate(R.menu.main_activity_menu, menu);
              toolbarButton = menu.findItem(R.id.action_button);
              return true;
          }
  
  toolbarButton.setIcon(R.drawable.ic_settings);
  </code></pre>
  
  <p>And it works perfectly, the problem is that it happens too fast, so i´d need to add an animation to the transition, but I don´t know how to add an animation to a toolbar button.
  Could somebody help me please?
  Thanks a lot!</p>