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What are the annotations for the id generator in java?


Asked by Esperanza Waters on Nov 29, 2021 Java



This tutorial explains the ID generator concept in details. The Java Persistence API including the EclipseLink distribution provides several types of primary key generation annotations. The @GeneratedValue consider the entry point for primary key generation, it provides the specification of generation strategies for the values of primary keys.
Subsequently,
@GeneratedValue Annotation. This annotation defines the types of primary key generation strategies. If this annotation is not used then application is responsible to populate and manage @Id field values itself. The use of the GeneratedValue annotation is only required to be supported for simple primary keys.
Next, The @SequenceGenerator annotation defines a primary key generator that may be referenced by name when a generator element is specified for the GeneratedValue annotation.A sequence generator may be specified on the entity class or on the primary key field or property. Target: Type, Method and Field
Similarly,
The @GenericGenerator annotation is used to create a 'named generator configuration' which can be later referenced using the @GeneratedValue annotation. In the rest of this post I will use the standard JPA annotations to configure the generators and not the @GenericGenerator annotation.
In addition,
The @Id annotation is inherited from javax.persistence.Id , indicating the member field below is the primary key of current entity. Hence your Hibernate and spring framework as well as you can do some reflect works based on this annotation. for details please check javadoc for Id