Why composite-id class must implement Serializable?

Question

If I make a composite-id class which doesn\'t implement Serializable like:

@Entity
@Table(name = \"board\")
public class Board {
    @Id
    @Column(name = \         


        

Answer 1

The session object needs to be serializable hence all objects referenced by it must be serializable as well. The id is used as a key to index loaded objects in the session. In case of CompositeId s the class itself is used as the id.