title: Display back button on action bar
body: <p>I'm trying to display a <code>Back button</code> on the <code>Action bar</code> to move previous page/activity or to the main page (first opening).
  And I can not do it.</p>
  
  <p>my code.</p>
  
  <pre><code>ActionBar actionBar = getActionBar();
  actionBar.setHomeButtonEnabled(true);
  </code></pre>
  
  <p>the code is in <code>onCreate</code>.</p>