Question: Does anyone know if GAE Datastore API supports user made classes and\or collections (e.g ArrayList etc)? 

I have the following code line:

```
entity.setProperty("offlineUsers",user._network._offlineUsers);

```

Where the property type is an ArrayList of a 'User' class I created . This line of code threw the following exception : 

```
java.lang.IllegalArgumentException: offlineUsers: com.example.computeroom.User is not a supported property type.

```

So reading the datastore guide <http://code.google.com/intl/iw/appengine/docs/java/datastore/entities.html> 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.

1- Just to be sure - is it true or not that the datastore has no support for user classes? 

2- What about collections/arrays - can it really be that there's no support for arrays ?  

 How am I supposed to store large lists of users/data ?

Answer: 
If you use Objectify, JPA or JDO, you will be able to store your own custom types.

<http://objectify-appengine.googlecode.com/>
i'm not sure whether it answers your question..
Some where while reading queries and indexes page i saw this

```
dataStore.put(Arrays.asList(person, weddingPhoto, babyPhoto, dancePhoto,    campingPhoto));

```