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Re: [eclipselink-users] JPA 2 @OrderColumn question
- From: James Sutherland <jamesssss@xxxxxxxxx>
- Date: Thu, 7 Jun 2012 07:44:49 -0700 (PDT)
- Delivered-to: firstname.lastname@example.org
Set, and HashSet are not ordered. These collection types have no order in
Java, so I'm not sure what expect???
If you want order, you need to use a List in Java. Lists are generally more
usable collection types.
You can add a constraint to your join table to enforce no duplicates.
> I was reading over the docs  regarding Eclipselink's support for
> @OrderColumn. It looks like this only applies to List and not Set. The
> reason I ask is because I have a ManyToMany bi-directional relationship
> (using a join table) which is a Set and is implemented with a HashSet
> because the collection can't have duplicates.
> I wanted to order the entries in this set using @OrderColumn, but it
> appears I can only apply this to List, however using List will break my
> unique requirement. Is this understanding correct?
> If so what is the recommended strategy for this case?
>  - http://wiki.eclipse.org/EclipseLink/Examples/JPA/2.0/OrderColumns
http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland
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