100 words

javax.persistence.IdClass - JPA annotation

javax.persistence
Annotation IdClass

Target:
Classes
Specifies a composite primary key class that is mapped to multiple fields or properties of the entity.

The names of the fields or properties in the primary key class and the primary key fields or properties of the entity must correspond and their types must be the same.

Example:

   @IdClass(com.acme.EmployeePK.class)
   @Entity
   public class Employee {
      @Id String empName;
      @Id Date birthDay;
      ...
   }

Since:
JPA 1.0
Class value
Primary key class
Primary key class
Since:
JPA 1.0

This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
Object DB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.