What is at com.caf.db.dao.JpaDao.persist(JpaDao.java:20)?
On Tue, Feb 19, 2013 at 5:08 PM, Aitor Iturriondobeitia < [email protected]> wrote: > hello > i an tring to build my firts openjpa app > i am readint this article ( > http://java.dzone.com/articles/jpa-implementation-patterns) and building > it > for this i make this: > 1.- generic interface: > public interface IGenericDao<K, E> { > void persist(E entity); > } > 2.- other interface, my interface. > public interface IWsSrvTrackRequest extends IGenericDao<Integer, > Wssrvtrackrequest>{ > void wsSrvRequestPersist(Wssrvtrackrequest request); > } > 3.- generic JPA-DAO: > public abstract class JpaDao<K, E> implements IGenericDao<K, E> { > protected Class<E> entityClass; > > @PersistenceContext > protected EntityManager entityManager; > > public JpaDao() { > ParameterizedType genericSuperclass = (ParameterizedType) > getClass().getGenericSuperclass(); > this.entityClass = (Class<E>) > genericSuperclass.getActualTypeArguments()[1]; > } > public void persist(E entity) { > entityManager.persist(entity); > } > } > } > 4.- my jpa-dao implementation (the Wssrvtrackrequest obj is one jpa object > (entity)). > public class JpaWsSrvTrackRequestDaoImpl extends JpaDao<Integer, > Wssrvtrackrequest> implements IWsSrvTrackRequest { > public void wsSrvRequestPersist(Wssrvtrackrequest request){ > entityManager.persist(request); > } > } > i am make one main class: > public static void main(String[] args) { > IWsSrvTrackRequest r = new JpaWsSrvTrackRequestDaoImpl(); > Wssrvtrackrequest v = new Wssrvtrackrequest(); > v.setWssrvreqIp("la ip"); > v.setWssrvreqOid("oid"); > v.setWssrvreqOiduser("oiduser"); > v.setWssrvreqRequest("la request"); > r.persist(v); > } > > but it always returns one nullpointerexception. > Exception in thread "main" java.lang.NullPointerException > at com.caf.db.dao.JpaDao.persist(JpaDao.java:20) > at com.caf.db.dao.ll.main(ll.java:20) > > Can you help me please? > > thanks > -- *Rick Curtis*
