how to access a list of objects array as a result of a JPQL's query

Question

Schema: each Employee may have many phone numbers and each phone number belongs to an Employee (a one-to-Many Relationship).

Using the following JPQL query: SELECT e, p FROM Employee e JOIN e.phones p,

How would you handle the resulting List<Object[]> from this query in your application code? In terms of accessing each employee and his/her phone number in the app. Code from that List<Object[]>? Using

em.createNamedQuery("..").getResultList().get(1)[]
// or
em.createNamedQuery("..").getResultList().get(2)[0]

results in error.

You misspelled createNamedQuery and getResulList in the code above. Does your actual code even compile? — Matt Ball
– Matt Ball, Commented May 11, 2012 at 15:15
results in error - you might want to elaborate on the exact error you get. — Thomas
– Thomas, Commented May 11, 2012 at 15:18
hi Thomas the result is: "Cannot cast from List<Object> to List<Object[]>" getResultList — arthur
– arthur, Commented May 11, 2012 at 16:14

Thomas · Accepted Answer · 2012-05-11 16:23:10Z

1

The problem most likely is that getResultList() returns a non generic List and thus you'd have to cast it to List<Object[]> first.

Assuming, your list has at least one entry this should work:

Employee e = (Employee)((List<Object[]>)em.createNamedQuery("..").getResultList()).get(0)[0];

Update:

Just for the reference: depending on the JPA version you use, you might get a List<Object> instead. In that case you could cast the value to Object[]:

Employee e = (Employee)((Object[])em.createNamedQuery("..").getResultList().get(0))[0];

edited May 11, 2012 at 16:23

answered May 11, 2012 at 15:14

Thomas

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1 Comment

arthur Over a year ago

thank for your help the problem lied in my app. code and i found it.

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