Saving order of a List in JPA

I have the following question about JPA:

Can I save the order of the elements in a java.util.List? In my application the order in which I put elements in the Lists is important but after I get those collections开发者_StackOverflow中文版 from the database the order is not the same (as expected). Can you show me a way to deal with this problem?

P.S. There is not a field in the entities that I put in the collections by which I can order them.

Rosen

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There are some hacky ways of doing this in JPA 1, but it's easiest to switch to a JPA 2 provider. The @OrderColumn annotation support is what you're looking for. Eclipselink have an ok tutorial on how to use it.

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JPA has 2 types of Lists. In JPA1 there is an "ordered list" (which is what you see, ordering defined by some SQL clause). In JPA2 you can have "ordered lists" or alternatively "indexed lists" (where the order of creation is preserved) ... the @OrderColumn referred to. Any implementation of JPA2 will have to support this e.g DataNucleus.

JDO has had indexed lists since day 1

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You can save the order of the elements in a java.util.List. In JPA 2.0, There is the good way to save the order of element by using @OrderColumn annotation.

For the details, you can refer this link Order Column (JPA 2.0)