How to autogenerate created or modified timestamp field?

Question

My entity class:

@Entity @Table(name = "user") public class User implements Serializable {     private static final long serialVersionUID = 1L;      @Id     @SequenceGenerator(name = "USER_ID_GENERATOR", sequenceName = "USER_SEQ")     @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "USER_ID_GENERATOR")     @Column(name = "user_id")     private long userId;       @Temporal(TemporalType.DATE)     private Date created;      @Temporal(TemporalType.DATE)     private Date modified;      //setters and getters... } 

I would like to CREATED and MODIFIED fields complement each other automatically when you create or modify the object. CREATED and MODIFIED fields should be of type TIMESTAMP.

How do I achieve that?

Answer 1

In 4.3 Hibernate with JPA, one can use "@CreationTimestamp" and "@UpdateTimestamp" directly in the date fields

CreationTimestamp java doc

UpdateTimestamp java doc

Answer 2

You can just create a new Date() whenever your instance is created, and then update the updated field whenever the entity gets updated:

private Date created = new Date(); private Date updated = new Date();  @PreUpdate public void setLastUpdate() {  this.updated = new Date(); } 

Don't provide a setter for any of these methods, only getters.