JPA EntityManagerFacade

Question

I have a problem with JPA EntityManagerFactory probably. My code

import entity.ProgrammEQ;
import entity.Student;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
/**
 *
 * @author Kristián
 */
public class Zapoctovka_priklad {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("zapoctovka_prikladPU");
        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();

        Student stud1 = new Student("Tom", "Pri");
        Student stud2 = new Student("Jan", "Pol");
        Student stud3 = new Student("Kris", "Str");

        em.persist(stud1);
        em.persist(stud2);
        em.persist(stud3);

        em.getTransaction().commit();

        em.close();
        emf.close();

        zaradNeprihlasenych("Aplikovaná informatika");
    }

    public static void zaradNeprihlasenych(String programmName) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("zapoctovka_prikladPU");
        EntityManager em = emf.createEntityManager();

        Query q1 = em.createQuery("SELECT a FROM Student a WHERE a.StudProgram = NULL");
        System.out.println("ahoj" + q1.getResultList().toString());

        em.getTransaction().begin();
        ProgrammEQ prog = new ProgrammEQ();
        prog.setIdEQ(programmName);
        prog.setStudentCount(0);

        List<Student> studenti = q1.getResultList();

        for (Student s : studenti) {
            System.out.println(s);
            s.setStudProgram(prog);
        }
        em.persist(prog);
        em.getTransaction().commit();

        em.close();
        emf.close();
    }

}

I have a problem. Becouse when I insert data into table student, it is okay. After that, when I close EntityManager and EntityManagerFactory, and in another function I want to add some properties, my table is empty. I tried a lot of things, but I dont know how to do that. When I called my query in main function, it returns right results. But when I call this query in function zoradNeprihlasenych, it returns null. When I remove emf.close() anotation, it works well. How to do that? I need to do that in another function outside the function.

Answer 1

Try to set Table Generation Strategy to create and Validation strategy to none in persistence.xml .