GWT + Spring + Hiberante. With no reason at all - spring

Question

I'm learning how to integrate Spring with GWT and RequestFactory by doing this following example. I got a NullPointerException and I don't know why. Can anyone help me?
Here is my code:
#Repository
public class EmployeeDAO implements IEmployeeDAO {
#PersistenceContext
private EntityManager entity;
#Override
public Employee findById(Long id) {
Query query = entity.createQuery("from Employee where id = :param");
query.setParameter("param", id);
query.setMaxResults(1);
return (Employee) query.getSingleResult();
}
#Transactional(propagation = Propagation.REQUIRED)
#Override
public void save(Employee employee) {
entity.merge(employee);
}
#Override
public void remove(Employee employee) {
entity.remove(employee);
}
#SuppressWarnings("unchecked")
#Override
public List<Employee> getAllEmployee() {
Query query = entity.createQuery("from Employee");
return query.getResultList();
}
// ...
}
and:
#Service(value = IEmployeeDAO.class, locator = DaoLocator.class)
public interface EmployeeRequestContext extends RequestContext {
Request<EmployeeProxy> findById(Long id);
Request<Void> save(EmployeeProxy employee);
Request<Void> remove(EmployeeProxy employee);
Request<List<EmployeeProxy>> getAllEmployee();
Request<EmployeeProxy> findOneByName(String name);
}
and:
#ProxyFor(Employee.class)
public interface EmployeeProxy extends EntityProxy {
Long getId();
String getName();
String getSurname();
void setId(Long id);
void setName(String name);
void setSurname(String surname);
Long getVersion();
void setVersion(Long version);
}
The NullPointerException is throw in GWT Entry Point in method:
protected void refresh() {
context = createFactory().employeeRequest();
final EmployeeProxy ep = context.create(EmployeeProxy.class);
ep.setName("Jan");
ep.setSurname("Kowalski");
ep.setVersion(new Long(0));
context.save(ep).fire(new Receiver<Void>() {
#Override
public void onSuccess(Void response) {
employeeList.add(ep);
}
#Override
public void onFailure(ServerFailure error) {
System.out.println("error podczas zapisu");
}
});
context = createFactory().employeeRequest();
context.getAllEmployee().fire(new Receiver<List<EmployeeProxy>>() {
#Override
public void onSuccess(List<EmployeeProxy> response) {
System.out.println(" " + response); // NULL
}
#Override
public void onFailure(ServerFailure error) {
}
});
System.out.println("Bedziemy wyswietlac dane!");
updateTable(employeeList);
}
the last one: method which create Factory:
private static EmployeeRequestFactory createFactory() {
EmployeeRequestFactory factory = GWT.create(EmployeeRequestFactory.class);
factory.initialize(new SimpleEventBus());
return factory;
}
Please help me...

Answer 1

Please print the stacktrace for the NullPointerException. Only then can we analyze the cause for the exception.