Nuovo tipo di errore
ho sbagliato la connessione al database?  
GRAVE: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
	at com.javatpoint.mypack.UserDao.register(UserDao.java:66)
	at org.apache.jsp.register_jsp._jspService(register_jsp.java:142)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
	
qui il codice della connessione al db e registrazione utente
public static int register(User user)throws HibernateException{
	int i=0;
	  SessionFactory factory=null; 
	 Session session = factory.openSession();
     Transaction tx = null;
     Integer employeeID = null;
     try{
        tx = session.beginTransaction();
        User employee = new User();//(fname, lname, salary);
        employeeID = (Integer)session.save(employee); 
        tx.commit();
     }catch (HibernateException e) {
        if (tx!=null) tx.rollback();
        e.printStackTrace(); 
     }finally {
        session.close(); 
     }
     return employeeID;
  }