Java Reference
In-Depth Information
The entity bean class
The entity bean class is just a POJO class annotated with the @Entity annotation.
A @NamedQuery specifies a findAll query, which selects all the entity instances.
An entity bean that has caching enabled is persisted to a database; the entity bean
is serialized by caches. Therefore, the entity bean class implements the java.
io.Serializable interface. Specify a serialVersionUID variable that is used by
serialization runtime to associate a version number with the serializable class:
private static final long serialVersionUID = 7422574264557894633L;
The database columns are mapped to entity bean properties, which are defined as
private variables. The getter setter methods for the properties are also defined. The
identifier property is specified with the @Id annotation. The @Column annotation
specifies that the id column is not nullable:
@Column(nullable = false)
private long id;
By default the id column of type INTEGER is mapped to a field of type Long . Modify
the id field to type long, as usually id values are of primitive type. The entity bean
class is listed next:
package model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
@NamedQuery(name = "Catalog.findAll", query = "select o from Catalog
public class Catalog implements Serializable {
private String author;
private String edition;
private static final long serialVersionUID = 7422574264557894633L;
@Column(nullable = false)
private long id;
private String journal;
private String publisher;
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