Avoiding Type Safety Warnings Using Hibernate Query.list()

Question

Is it possible to avoid cast warnings after using createQuery().list?

//Type safety: The expression of type List needs unchecked conversion to conform to Lis         


        

Answer 1

Since JPA 2.0 , EntityManager has added following overloaded createQuery()/createNamedQuery() methods that return TypedQuery to solve the propblem:

TypedQuery entityManager.createQuery(CriteriaQuery criteriaQuery)


TypedQuery entityManager.createQuery(java.lang.String qlString, java.lang.Class resultClass)


TypedQuery entityManager.createNamedQuery(java.lang.String name, java.lang.Class resultClass)

Example:

@Repository
public class UsersRepositoryImpl implements IUsersRepository {

        @PersistenceContext(unitName="SPRING_BOOT_JPA_DS_PU")

    private EntityManager entityManager;

    @Override
    public List listUser() {
        String queryString = "SELECT U FROM " + User.class.getName() + " U";
        // Query query =entityManager.createQuery(queryString);
        // Use TypedQuery instead of Query
        // Requires JPA 2.0
        TypedQuery query = entityManager.createQuery(queryString, User.class);
        List resultList = query.getResultList();

        return resultList;
    }


    }