Question

I created the entity classes of my database with NetBeans. I believe I know how to use EntityManager

(Class) db.createNamedQuery(String name);

but I don’t know where to put the statement (database link, login, password) so I learned how to query with

(JDBC4ResultSet) statement.executeQuery(String query);

but it returns the set which I don’t know how to transform into Entity class… something like

(Class) statement.execureQuery(String query).toEntity(Class);

would be nice. 😉

Answer 1

Ok, First you need to get an EntityManager from entity manager factory with your persistance unit name (which will be configured in persistance.xml). And then you create an EntityManager.

    EntityManagerFactory emf=Persistence.createEntityManagerFactory("persistance_unit_name");
    EntityManager em=emf.createEntityManager();
    Query query = em.createNamedQuery("namedQueryName"); //this returns a query
    List<ENTITIY> result = query.getResultList();

This is just an heads up, You can google ‘jpa example’ to find out more working examples.