Insert multiple rows with autoincrement id

Question

I need to insert multiple rows to a table which has an autoincrement PK (unique), e.g:
Entity:
public Class Entity{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "id")
Private Long id;
Facade:
@PersistenceContext(unitName = "xx-enterprise-ejbPU")
protected EntityManager em;
public void create(Entity entity) {
em.persist(entity);
Service Class:
public Class Service implements ServiceLocal{
@EJB
private XxxFacadeLocal xxxFacade;
public void saveEntity(Entity entity){
xxxFacade.create(entity)
ManageBean:
public Class ManageBean
@EJB
private ServiceLocal service;
public void doSave(ActionEvent event)
service.saveEntity(entity1); //entity.id is set to null, suppose to be generated by DB auto_increment, i.e. insert 3 rows with 3 different ids
service.saveEntity(entity2);
service.saveEntity(entity3);
The result is: Key duplication error on inserting entity2, but entity1 is inserted into DB with id auto increased correctly.
If I insert only one row each time for test purpose, everything works as expected.
But what I need is to insert multiple rows. How to do it?
Thank you in advance.

Answer 1

Like this (although the @Basic annotation is very much unnecessary). So if it isn't happening you must have made a mistake somewhere. Are you sure the ID column actually has auto_increment?
Also if you are using Hibernate as the persistence provider and you put it on the classpath, check the packages of the annotations you are using; Hibernate and JPA share some with the same name unfortunately.