I haven't got much experience with Hibernate, I just started with it last weekend for a school project. I already managed to do some things but there's just one thing I can't get to work. One of the classes I use contains a list (it actually contains 2 collections). When Hibernate loads those lists, the lists contain all necessary objects, but they also contain a lot of null-pointers. Is this normal behavior?

I use the following code to load the lists:

<list name="competenties" lazy="true" inverse="true" cascade="all">
<key column="comCompRooster"/>
<index column="comNr"/>
<one-to-many class="Competentie"/>
</list>

<list name="groepen" lazy="true" inverse="true" cascade="all">
<key column="grpCompetentieRooster"/>
<index column="grpNr"/>
<one-to-many class="Groep"/>
</list>

Hopefully someone can help me with this.

if you have any inconsistencies in the contuinity of your index column, hibernate will insert nulls to fill those voids.

I don't know where that sentence came from but I'll explain it better. If for a specific collection, in your db you have the index column with values

0,1,2,3,4,5,6 you will get a list back with no nulls

if, however, your index column has the values
1,2,3,4,6

you will get a list back with null values in the '0' spot and the '5' spot.

Hibernate expects it to start at 0 and have a continuous set of integers

I had the same problem. I used a Set instead. It works just fine now. The only thing I can't do right now, is list.get(index). But then you could always do a session.createQuery("select * from table where id = ?");