Question

Im querying a database using JPQL but I cannot retrieve the ‘Report’ table’s rows using List. This is a section of my code:

...
EntityManagerFactory emf = Persistence.createEntityManagerFactory("hibernate");
EntityManager em = emf.createEntityManager();
EntityTransaction tx = em.getTransaction();
tx.begin();
Query query = em.createQuery("SELECT r.title, r.company FROM Report as r");
     List<Report> itemList = query.getResultList();
     for (Report item : itemList)
     {
        System.out.println("Item: " + item.getCompany());
  }

The output is:

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to maps.Report at hello.Test.main(Unknown Source)

Java Result: 1

What am I doing wrong? Why I am not allowed to do the casting?

Answer 1

Your query doesn’t select instances of Report. It selects two fields: r.title and r.company. In this case, JPA returns a list of Object[]. Each Object[] of the list contains two elements: the title and the company.

Use select r from Report r to select Report instances.