NullPointerException when accessing EntityManagerFactory from within EJB

Question

Hello everyone,
I am having trouble getting an EJB to work properly with persistence. Here is the code for my EJB:
package HelpDesk.ejb;
import javax.ejb.Stateless;
import HelpDesk.entity.Tecnico;
import javax.persistence.*;
import javax.persistence.EntityManagerFactory;
@Stateless
public class HelpDeskManager implements HelpDeskManagerInterface {
   @PersistenceUnit(unitName="HelpDeskPU")
   EntityManagerFactory emf;
  public void newTecnico(String nombre, String username, String privilegio, String password)
      javax.persistence.EntityManager em = emf.createEntityManager();
      Tecnico tec = new HelpDesk.entity.Tecnico(nombre, username, privilegio, password);
      em.persist(tec);     
}The error happens on the line: javax.persistence.EntityManager em = emf.createEntityManager();
This method is then called from a servlet which has the following code on its doGet() method:
      response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            HelpDesk.ejb.HelpDeskManager hdm = new HelpDesk.ejb.HelpDeskManager();
            hdm.newTecnico(request.getParameter("nombre"), request.getParameter("username"), request.getParameter("privilegio"), request.getParameter("password"));
            out.println("Técnico creado exitosamente.");
            response.sendRedirect("index.jsp");
        catch(Exception ex){out.println(ex.getMessage());}
        finally {
            out.close();
        }Using this try statement simply causes the word "null" to be output to the browser. Without the try statement, I get the NullPointerException on the app server logs. I am using Netbeans 6.5/ Glassfish v2. I can guarantee that the Persistence Unit is correctly configured and that a connection pool has been defined in Glasfish for this database, as well as a JNDI name for it, though I do not know if it's necessary to register the EJB as a JNDI name as well.
Any advice will be truly appreciated, as I am rather new to EJB technology. Thank you.

Answer 1

Hello again, thanks for your quick reply,
I tried it out the way you suggested, but I now get the following error displayed on my browser:
type Exception report
message
descriptionThe server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: PWC1391: Servlet.init() for servlet newTecnico threw exception
root cause
java.lang.RuntimeException: WEB5002: Exception in handleBeforeEvent.
root cause
com.sun.enterprise.InjectionException: Exception attempting to inject Unresolved Ejb-Ref help_desk.servlet.newTecnico/hdm@jndi: HelpDesk.ejb.HelpDeskManager@[email protected]@Session@null into class help_desk.servlet.newTecnico
root cause
javax.naming.NameNotFoundException: HelpDesk.ejb.HelpDeskManager#HelpDesk.ejb.HelpDeskManager not foundI believe it is because I need to define the EJB as a JNDI resource. However, I am unsure how to go about this. When I try to do create a new JNDI resource via the Glassfish Admin Console, it asks for several fields, including Resource Type and Resource Factory. I think Resource Type can be the fully qualified class name, but my EJB doesn't have any factory classes associated with it.
Thanks again for the information. your help is greatly appreciated!