Can you post a stack trace? It's not helpful if we don't know what line of
code is causing the exception.
On Mon, Feb 15, 2010 at 11:53 PM, sujata pagar wrote:
> Dear all,
>I am getting NullPointerException in the following code for the
> transaction tx. Please reply me soon.
>
> Code:
>
> package com.wissen.enterprisebysush.
> server;
>
> import java.util.List;
>
> import javax.jdo.JDOHelper;
> import javax.jdo.PersistenceManager;
> import javax.jdo.PersistenceManagerFactory;
> import javax.jdo.Transaction;
> import javax.persistence.EntityManager;
> import javax.persistence.EntityManagerFactory;
> import javax.persistence.EntityTransaction;
> import javax.persistence.Persistence;
> import javax.persistence.Query;
>
> import com.google.gwt.user.client.Window;
> import com.google.gwt.user.server.rpc.RemoteServiceServlet;
> import com.wissen.enterprisebysush.client.GreetingService;
> import com.wissen.enterprisebysush.server.domainobject.Department;
> import com.wissen.enterprisebysush.server.domainobject.Employee;
>
> /**
> * The server side implementation of the RPC service.
> */
> @SuppressWarnings("serial")
> public class GreetingServiceImpl extends RemoteServiceServlet implements
> GreetingService {
>
> EntityManagerFactory emf =
> Persistence.createEntityManagerFactory("transactions-optional");
>
> public String greetServer(String input) {
> String serverInfo = getServletContext().getServerInfo();
> String userAgent = getThreadLocalRequest().getHeader("User-Agent");
> return "Hello, " + input + "!I am running " + serverInfo +
> ".It looks like you are using:" + userAgent;
> }
>
> @SuppressWarnings("unchecked")
> public void addDept(String dept_name, String dept_head) {
>
> EntityManager em = null;
>
> try {
> em = emf.createEntityManager();
> em.getTransaction().begin();
> Department d = new Department();
> d.setDept_name(dept_name);
> d.setHead(dept_head);
>
> Query q = em.createQuery("select from
> com.wissen.enterprisebysush.server.domainobject.Department d");
> List deptList = q.getResultList();
>
> for (Department dept : deptList) {
> System.out.println("Department name: " +
> dept.getDept_name());
> }
>
> em.persist(d);
>
> } finally {
> em.getTransaction().commit();
> em.close();
>
> }
>
> }
>
> public void addEmp(String emp_name, String emp_sal, String did) {
> EntityManager em = emf.createEntityManager();
> try {
>
>
> String s = did;
>
> EntityTransaction transaction = em.getTransaction();
> transaction.begin();
> System.out.println("value of Department_name is::" + s);
> System.out.println("Transaction is active and
> is::"+transaction);
>
> //Query q = em.createQuery("select dept_id from
> com.wissen.enterprisebysush.server.domainobject.Department d where
> d.dept_name = ?1");
> //q.setParameter(1, s);
> //System.out.println("Name of Department is::" +
> s);
> //Department dept = (Department)
> q.getSingleResult();
>
> Query q = em.createQuery("select from
> com.wissen.enterprisebysush.server.domainobject.Department d");
> Department dept = (Department) q.getResultList().get(0);
> System.out.println("Name of Department is::" +
> dept.getDept_name());
>
> //System.out.println("Query executed
> Successfully!!" + q.getSingleResult());
> Employee e = new Employee();
> e.setEmp_name("Ritesh Navandar");
> e.setEmp_sal("5000");
> e.setDepartment(dept);
> em.persist(e);
>
> System.out.println("Transaction: " + transaction);
>
> transaction.commit();
> em.close();
>
> } catch (NullPointerException e) {
> e.printStackTrace();
> System.out.println("Exception::" + e.getCause());
> } finally {
>
> }
> }
>
> }
>
>
> --
> Regards,
> Sujata...
>
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--
Ikai Lan
Developer Programs Engineer, Google App Engine
http://googleappengine.blogspot.com | http://twitter.com/app_engine
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