NullPointerException lors d'un appel à un DAO.

Bonjour,

Dans un projet, lorsque je fait appel à la méthode "get_student_by_login" du DAO suivant :

Code:

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package be.promosoc.dao;
import org.hibernate.HibernateException;
import org.hibernate.classic.Session;
import org.hibernate.criterion.Restrictions;
import org.hibernate.Criteria;
import be.promosoc.models.Student;
 
 
public class StudentDAO {
public static Student get_student_by_id(Long id){
	Student student= new Student();
	try {
		Session session = SessionManagement.getSessionFactory().getCurrentSession();
		student = (Student) session.load(Student.class,id);
		SessionManagement.getSessionFactory().close();
 
	} catch (HibernateException ex){
		System.err.println("Error when selecting user by userID "+ ex);
	} 
	return student;
 
}
//REMSEB: Hibernate va faire un select student sur l ID
 
public static Student get_student_by_login(String login){
	Student student= new Student();
	try {
		Session session = SessionManagement.getSessionFactory().getCurrentSession();
		session.beginTransaction();
		Criteria query = session.createCriteria(Student.class).add(Restrictions.like("login", login).ignoreCase());
		student = (Student) query. uniqueResult();
		SessionManagement.getSessionFactory().close();
 
	} catch (HibernateException ex){
		System.err.println("Error when selecting user by userID "+ ex);
	} 
	return student;
}
public static void insert_student(Student student){
	try {
		Session session = SessionManagement.getSessionFactory().getCurrentSession();
		session.beginTransaction();
		session.save(student);
		session.getTransaction().commit();
		SessionManagement.getSessionFactory().close();
	}catch(HibernateException ex){
		System.err.println("Error when inserting user "+ ex);
}
 
}}

je me retrouve avec l'exception suivante.

Code:

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Exception in thread "main" java.lang.NullPointerException
	at org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge.nextTimestamp(RegionFactoryCacheProviderBridge.java:93)
	at org.hibernate.impl.SessionFactoryImpl.openSession(SessionFactoryImpl.java:678)
	at org.hibernate.context.ThreadLocalSessionContext.buildOrObtainSession(ThreadLocalSessionContext.java:142)
	at org.hibernate.context.ThreadLocalSessionContext.currentSession(ThreadLocalSessionContext.java:103)
	at org.hibernate.impl.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:695)
	at be.promosoc.dao.StudentDAO.get_student_by_login(StudentDAO.java:28)
	at DbLoader.main(DbLoader.java:26)

Je ne comprend pas ou il y a une erreur, pouvez vous m'aider?

D'avance merci.