Question

Assuming I have a class A as follows:

class A{    int id;    int getId(){};    void setId(int id){}; } 

And a class B as follows:

@Entity @Table(name='B') class B extends A{    string name;     @Column(length=20)    string getName(){}    void setName(){} } 

How can I annotate the inherited id field from A so that Hibernate/JPA knows it is the Id for the entity? I tried simply placing @Id on the field in A but this didn’t work. I tried making A an entity as well and this also didn’t work.

Answer 1

Assuming you don’t want the superclass itself to represent an entity, you can use @MappedSuperclass on the super class to have subclasses inherit the properties for persistence:

@MappedSuperclass class A{    int id;    @Id    int getId(){};    void setId(int id){}; } 

Consider making the superclass abstract. See this section of the doc for more details.