I am having a problem when updating a particular entry inside a loop using hibernateSessionFactory.currentSession getting a error i.e hibernateNonUniqueException a different object with the same identifier value is already associated with a session.The following situtaion is depicted below

public Login saveTeacher(TeacherDto teacherObject, List<ExamDto> examsObject, Teacher_DeptDto departmentsObject) throws Exception {
Session session = HibernateSessionFactory.currentSession();
Transaction tx = session.beginTransaction();
Login lg = new Login();

try {
for(Iterator iterator = examsObject.iterator();iterator.hasNext();){

ExamDto exobj=(ExamDto)iterator.next();

String Query = "update ExamDto e set e.id = :teacherId where e.examId = :eId";
Query query = session.createQuery(Query);
query.setParameter("teacherId", teacherObject.getId());
query.setParameter("eId", exobj.getExamId());
session.update(exobj); //***This the area where the problem occurs
}


session.save(teacherObject);

session.save(departmentsObject);
tx.commit();


Please help how this can be rectified ...i n case when I am using openSession() the problem doesn't occur.