Erreur "NullPointerException"
Bonjour,
Je suis en train de développer un exercice en JEE, donc j'ai créé une base de données avec les tables Etudiant, Devoir et Note.
J'ai créé une méthode pour récupérer une liste d'étudiants mais quand je crée un étudiant, j'obtiens l'erreur suivante :
Citation:
An error occurred attempting to roll back the transaction
java.lang.NullPointerException
Voici mon code
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| package fr.note;
import fr.note.entites.Etudiant;
import fr.note.service.ClientEjbNoteRemote;
import java.util.List;
import javax.ejb.EJB;
public class client_lourd {
@EJB
private static ClientEjbNoteRemote ejbNote;
private static final int NUM =7;
private static final String NOM="sam";
private static final String PRENOM = "sam";
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
/*List<Etudiant> liste = ejbNote.ListEtudiant();
for(Etudiant e : liste){
System.out.println(e.getPrenom() + "\t" + e.getNom());
}*/
Etudiant etudiant = new Etudiant(NUM);
ejbNote.InsererEtudiant(etudiant);
}
} |
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| package fr.note.service;
import fr.note.entites.Etudiant;
import java.util.List;
import javax.ejb.Remote;
@Remote
public interface ClientEjbNoteRemote {
public List<Etudiant> ListEtudiant();
public void InsererEtudiant(Etudiant etudiant);
} |
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| package fr.note.persisatnce;
import fr.note.entites.Etudiant;
import fr.note.persisatnce.exceptions.NonexistentEntityException;
import fr.note.persisatnce.exceptions.RollbackFailureException;
import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Query;
import javax.persistence.EntityNotFoundException;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import javax.transaction.UserTransaction;
public class EtudiantJpaController implements Serializable {
public EtudiantJpaController(UserTransaction utx, EntityManagerFactory emf) {
this.utx = utx;
this.emf = emf;
}
private UserTransaction utx = null;
private EntityManagerFactory emf = null;
public EntityManager getEntityManager() {
return emf.createEntityManager();
}
public void create(Etudiant etudiant) throws RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
em.persist(etudiant);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public void edit(Etudiant etudiant) throws NonexistentEntityException, RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
etudiant = em.merge(etudiant);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
String msg = ex.getLocalizedMessage();
if (msg == null || msg.length() == 0) {
Integer id = etudiant.getNumEtudiant();
if (findEtudiant(id) == null) {
throw new NonexistentEntityException("The etudiant with id " + id + " no longer exists.");
}
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public void destroy(Integer id) throws NonexistentEntityException, RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
Etudiant etudiant;
try {
etudiant = em.getReference(Etudiant.class, id);
etudiant.getNumEtudiant();
} catch (EntityNotFoundException enfe) {
throw new NonexistentEntityException("The etudiant with id " + id + " no longer exists.", enfe);
}
em.remove(etudiant);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public List<Etudiant> findEtudiantEntities() {
return findEtudiantEntities(true, -1, -1);
}
public List<Etudiant> findEtudiantEntities(int maxResults, int firstResult) {
return findEtudiantEntities(false, maxResults, firstResult);
}
private List<Etudiant> findEtudiantEntities(boolean all, int maxResults, int firstResult) {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
cq.select(cq.from(Etudiant.class));
Query q = em.createQuery(cq);
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
} finally {
em.close();
}
}
public Etudiant findEtudiant(Integer id) {
EntityManager em = getEntityManager();
try {
return em.find(Etudiant.class, id);
} finally {
em.close();
}
}
public int getEtudiantCount() {
EntityManager em = getEntityManager();
try {
CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
Root<Etudiant> rt = cq.from(Etudiant.class);
cq.select(em.getCriteriaBuilder().count(rt));
Query q = em.createQuery(cq);
return ((Long) q.getSingleResult()).intValue();
} finally {
em.close();
}
}
} |
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| package fr.note.service;
import fr.note.entites.Etudiant;
import fr.note.persisatnce.EtudiantJpaController;
import fr.note.persisatnce.exceptions.RollbackFailureException;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.ejb.Stateless;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
@Stateless
public class ClientEjbNote implements ClientEjbNoteRemote, ClientEjbNoteLocal {
@Override
public List<Etudiant> ListEtudiant(){
EntityManagerFactory emf = Persistence.createEntityManagerFactory("NFE114-Note-JEE-ejbPU");
EtudiantJpaController daoEtudiant = new EtudiantJpaController(null, emf);
List<Etudiant> liste = daoEtudiant.findEtudiantEntities();
return liste;
}
@Override
public void InsererEtudiant(Etudiant etudiant){
try {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("NFE114-Note-JEE-ejbPU");
EtudiantJpaController daoEtudiant = new EtudiantJpaController(null,emf);
daoEtudiant.create(etudiant);
} catch (RollbackFailureException ex) {
Logger.getLogger(ClientEjbNote.class.getName()).log(Level.SEVERE, null, ex);
} catch (Exception ex) {
Logger.getLogger(ClientEjbNote.class.getName()).log(Level.SEVERE, null, ex);
}
}
} |
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| package fr.note.service;
import fr.note.entites.Etudiant;
import fr.note.persisatnce.exceptions.RollbackFailureException;
import java.util.List;
import javax.ejb.Local;
@Local
public interface ClientEjbNoteLocal {
public List<Etudiant> ListEtudiant();
public void InsererEtudiant(Etudiant etudiant);
} |
Quelqu'un saurait-il m'indiquer d'où peut venir le problème ?
Merci d'avance pour votre aide.
