title: Can't "unselect" listview item
body: <p>I was able to get the background changed of an individual listview item in a setOnItemClickListener with</p>
  
  <pre><code>view.setBackgroundResource(R.color.green); 
  </code></pre>
  
  <p>I only need one selected at a time so when the other list items are clicked, I tried <code>lv.invalidate()</code> and <code>lv.getChildAt(0).invalidate()</code> but neither worked and the second causes null pointer exception. Any ideas for putting the color back?</p>