title: Volley request with multiple resources
body: <p>I have a problem to display data from multiple resources by using volley.</p>
  
  <p>Parts of this JSON-Response of the tracks should be displayed in a ListView:
  <code> 
  {"tracks":[{"owner":"2","idtrack":"6","start":"2014-02-06 21:52:07","end":null,"name":"Track987"},{"owner":"1","idtrack":"10","start":"2014-02-19 20:38:44","end":null,"name":"TestTrack4"},{"owner":"2","idtrack":"13","start":"2014-03-19 20:58:57","end":null,"name":"Ttt54"},{"owner":"1","idtrack":"15","start":"2014-06-04 09:59:35","end":null,"name":"Test"}]}
  </code>
  But that's not my problem.
  I do this by an adapter.</p>
  
  <p>In every row of my ListView the name and the starttime are displayed. For Example:</p>
  
  <ul>
  <li>Track987 </li>
  <li>Thu Feb 06 21:52:07 MEZ 2014</li>
  </ul>
  
  <p>So far so good.
  Now, I also want to display the owner. But I have only the id of an user in my JSON-Response. I want to display the owner name.
  I can get the name  by an other JSON-Request:
  <code> {"iduser":"2","email":"sl@email.com","lastname":"Lastname","firstname":"Firstname}</code></p>
  
  <p>What is the best way to solve my problem that one row looks like this:</p>
  
  <ul>
  <li>Track987</li>
  <li>Thu Feb 06 21:52:07 MEZ 2014</li>
  <li>Firstname Lastname</li>
  </ul>
  
  <p>At the moment when all tracks are loaded by volley and i notify the adapter, the information about the owner aren't present. So I get a NullPointerException from my CustomAdapter.</p>
  
  <p>Which solution would be the best?</p>