How to eliminate "unchecked" warnings when using JPA

Question

I do a lot of querying with javax.persistence. And Java forces me to either suffer warnings or @Suppress them, neither of which feels right.

@SuppressWarnings("unchecked")
@Override
public List<Area> getArea(Province province) {
    Query qry = em.createQuery("Select c from Area c where c.province = ?1");
    qry.setParameter(1, province);
    return qry.getResultList();
}

How do I eliminate the warning in the above code?

score 10 · Accepted Answer · edited Feb 24 '13 at 12:04

10

If you're using JPA annotations, use TypedQuery instead of Query:

TypedQuery<Area> qry = em.createQuery(
    "Select c from Area c where c.province = ?1", Area.class);

edited Feb 24 '13 at 12:04

Perception

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answered Feb 24 '13 at 11:50

Igor Rodriguez

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I would also suggest the OP to use named parameters – gd1 Feb 24 '13 at 12:09
If I do that I get a `Type mismatch: cannot convert from Query to TypedQuery`. The `em.createQuery` will only generate a plain Query as a result. – Johan Feb 24 '13 at 12:13
Check the second parameter in the createQuery(String, class) method. You are passing the type. – Igor Rodriguez Feb 24 '13 at 12:14
Ok, got it, you need to add the `Area.class` to the createQuery. – Johan Feb 24 '13 at 12:15

score 1 · Answer 2 · edited May 23 '17 at 11:52

1

You can use the Criteria API to avoid this. Check out this question for info on how to use it.

edited May 23 '17 at 11:52

Community

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answered Feb 24 '13 at 11:45

Barend

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+1, however in this case it is not necessary to use the Criteria API, but the code of the OP can be ported to TypedQuery that uses generics and requires less rework. – gd1 Feb 24 '13 at 12:08
The convoluted way in which the Criteria API forces you to writes queries makes my head hurt. It's an exercise in masochism. – Johan Feb 24 '13 at 12:10

How to eliminate "unchecked" warnings when using JPA

2 Answers2