I have three bens: Setor, Quadra, Lote . Setor has two collection attributes: quadra and lote. Quadra has one collection attribute: lote. I'm using java.util.Collection to handle such collections, but i'm gettig this Exception:

java.lang.ClassCastException
at net.sf.hibernate.type.SetType.wrap(SetType.java:27)
at net.sf.hibernate.impl.SessionImpl.wrap(SessionImpl.java:2519)
at net.sf.hibernate.impl.SessionImpl.wrap(SessionImpl.java:2459)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:708)
at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:605)

This is the piece of code where this is happening:

quadra.setLotes(lotes);

where quadra is an instance of bean Quadra, setLotes is the mutator method of the lotes collection attribute in Quadra, and lotes (inside the brackets) is a collection of Lote.

This is a piece of the mapping file for the Setor class:

<set name="lotes" inverse="true" cascade="all">
<key column="id_setor"/>
<one-to-many class="beans.Lote"/>
</set>


<set name="quadras" inverse="true" cascade="all">
<key column="id_setor"/>
<one-to-many class="beans.Quadra"/>
</set>

So, why am I getting that excepetion ?

Thanks

Ot

In addition to using Middlegen you might want to check out the round trip tools offered as part of the Hibernate extensions. These allow you to start with a DB, use Middlegen to generate hbm and hbm2java to create a java class file. The class file will "work" with the mapping and database but might not be the exact functionality you need but it is a good starting point. Check out http://hibernate.org/102.html

HTH,
Timothy Vogel

Your advide just fits what I've done some minutes ago. I've substituted every java.util.Collection for a java.util.Set , and it works fine now. I'm also new to Hibernate, and the deeper I go in my project, the more I notice how full of possibilities this tool is.

Thanks a lot for the help. I'm gonna try MiddleGen ;)