title: Google App Engine Supported Datastore Types
body: <p>Does anyone know if GAE Datastore API supports user made classes and\or collections (e.g ArrayList etc)?  </p>
  
  <p>I have the following code line:</p>
  
  <pre><code>entity.setProperty("offlineUsers",user._network._offlineUsers);
  </code></pre>
  
  <p>Where the property type is an ArrayList of a 'User' class I created . This line of code threw the following exception : </p>
  
  <pre><code>java.lang.IllegalArgumentException: offlineUsers: com.example.computeroom.User is not a supported property type.
  </code></pre>
  
  <p>So reading the datastore guide <a href="http://code.google.com/intl/iw/appengine/docs/java/datastore/entities.html" rel="nofollow">http://code.google.com/intl/iw/appengine/docs/java/datastore/entities.html</a> raises my  suspicion that you cannot store classes you created , or collections/arrays - I can only see support for basic types (int,boolean etc) and no mention of user defined objects or arrays\collections.</p>
  
  <p>1- Just to be sure - is it true or not that the datastore has no support for user classes?  </p>
  
  <p>2- What about collections/arrays - can it really be that there's no support for arrays ?<br>
     How am I supposed to store large lists of users/data ?  </p>