title: Android - Add "Up Botton" for lower level activity with appcompat theme?
body: <p>I am following the starter android development guide and trying to add a up bottom for lower level activities. However, I get an null pointer error when executing 
  getActionBar().setDisplayHomeAsUpEnabled(true);</p>
  
  <p>Is it because of my theme (appcompat created by Eclipse automatically) doesn't support this?</p>
  
  <p>How can I resolve it? thanks!</p>