Java Reference
In-Depth Information
In the deleteSomeData() method, we shall delete some data. For example, we shall
delete the magazine catalog for Oracle Magazine . First we create a Query object to
find a Catalog entity instance by journal name:
Query q = em.createNamedQuery("findCatalogByJournal");
Set the journal name to Oracle Magazine using the setParameter() method:
q.setParameter("journal", "Oracle Magazine");
Get a List of Catalog s for the specified query using the getResultList() method:
List list = q.getResultList();
Iterate over the List and remove the Catalog entities using the remove() method:
for (Object catalog : list) {
The CatalogSessionEJBBean class is listed next:
package model;
import javax.ejb.*;
import javax.persistence.*;
import java.util.*;
@Stateless(name = "CatalogSessionEJB", mappedName = "EJB3-SessionEJB")
public class CatalogSessionEJBBean implements CatalogSessionEJBRemote
First, inject an EntityManager :
@PersistenceContext(unitName = "em")
EntityManager em;
Define the getter methods:
public List<Edition> getAllEditions() {
ArrayList<Edition> editions = new ArrayList<Edition>();
Query q = em.createNamedQuery("findEditionAll");
for (Object ed : q.getResultList()) {
return editions;
public List<Section> getAllSections() {
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