Mapping Collections of Collections?

jantzen · **Joined:** Thu Jun 22, 2006 5:13 am **Posts:** 1

It's looking to me like the answer is "no", but is there any way to map nested collections?

My data structure looks like this:

Code:

LinkedHashMap<Integer, Set<String>> mappedSet = new LinkedHashMap<Integer, Set<String>>();

Can that be mapped as is or should I instead find a way to decompose into simpler Java objects?

Thanks Much,
David

hlfsousa · **Posted:** Fri Jun 23, 2006 8:07 am

I am no expert, but as far as I know you can only make a mapping of keys (String, Number and subclasses) to mapped entities. java.util.Set is not an entity, so my immediate answer would be no. However, you can make a mapped entity implement java.util.Set. Now that would be akward, but anyway...

The other path would be to create an entity with two (or more according to your need) properties: an identifier and a one-to-many relationship. This would be the Set elements' type. I think this looks more elegant than making some entity implement java.util.Set.