Exception in thread "main" org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.abe.entity.Student#0]

at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:179)

at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135)

at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:206)

at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)

at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:191)

at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)

at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)

at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:764)

at org.hibernate.internal.SessionImpl.save(SessionImpl.java:756)

at org.hibernate.internal.SessionImpl.save(SessionImpl.java:752)

at com.abe.test.Test.add(Test.java:35)

at com.abe.test.Test.main(Test.java:16)