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JPA 2.0 enums with custom values

Let's consider we have this enum



public enum EmpType {

FULL_TIME("e1"), PART_TIME("e2");

private String val;

private EmpType(String val) {

this.val = val;

}

@Override

public String toString() {

return val;

}

}

And the entity



@Entity
@NamedQueries({
@NamedQuery(name="Employee.findByEmployeeType", query="SELECT e FROM Employee e WHERE e.employeeType = ?1")
})

@Access(AccessType.FIELD)

public class Employee implements Serializable {

private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@Transient
private EmpType empType;


public Long getId() {

return id;

}


public void setId(Long id) {

this.id = id;

}


public EmpType getEmpType() {

return empType;

}


public void setEmpType(EmpType empType) {

this.empType = empType;

}


@Access(AccessType.PROPERTY)
@Column(name="employee_type")
protected String getEmployeeType() {

return empType.toString();

}


protected void setEmployeeType(String employeeType) {

for ( EmpType empType : EmpType.values() ) {

if ( empType.toString().equals(employeeType)){

this.empType = empType;

}

}

}


@Override
public String toString() {

return " ID : " + id + ", employee type : " + empType;

}


}


Note : Please checkout how i'm using @Access annotations at two different places, they are mandatory.


public class Main {


public static void main(String[] args) {

Main m = new Main();

Employee e = new Employee();

e.setEmpType(EmpType.PART_TIME);

em.persist(e); // assume we are persisting this entity


m.executeQuery(EmpType.PART_TIME);


}


public void executeQuery(EmpType emptType) {

EntityManagerFactory emf = Persistence.createEntityManagerFactory("PrepApp1PU");

EntityManager em = emf.createEntityManager();


Query query = em.createNamedQuery("Employee.findByEmployeeType");

query.setParameter(1, emptType.toString());

List list = query.getResultList();

System.out.println ( list.get(0) );


}


}




the above code will save entity as follows


ID EMPLOYEE_TYPE

1 e2


Also please carefully checkout how i'm searching employees based on enums. Also carefully checkout getEmployeeType(), setEmployeeType method signatures



the executeQuery method will print this

ID : 1, employee type : e2

Comments

Mansour's Page said…
This comment has been removed by the author.
Mansour's Page said…
This comment has been removed by the author.
Mansour's Page said…
Intesar,
you are using the enum as a placeholder for string values. Basicaly enum is used just like any class or interface. You can put your values in an entity class as well.

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