How do these Hibernate objects differ? [duplicate]

Question

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Possible Duplicate:
Hibernate: different object with the same identifier value was already associated with the session

Why does some objects I get in Hibernate exceptions appear like this when they are printed out with the @ symbol:

Cannot remove object

db.item.model.Inventory@21d321bb

But some appear like this:

org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [db.item.model.Inventory#9369629]

With the identifier after # symbol?

Answer 1

The identifier after the # is the primary key of the object in the table.

A NonUniqueObjectException occurs when two objects with the same identifier (primary key) are added to the session.

db.item.model.Inventory@21d321bb is output by the default equals method i.e. Object.equals().

Answer 2

db.item.model.Inventory@21d321bb refers to a memory address.

db.item.model.Inventory#9369629 refers to an entity with ID 9369629.

Answer 3

db.item.model.Inventory@21d321bb is a certain instance. [db.item.model.Inventory#9369629] are two or more instances with @Id 9369629.