I am creating a Java EE application using jpa.
I am getting the following error when the code is run on server
[2/25/12 22:56:31:371 IST] 00000047 SystemOut O hello
[2/25/12 22:56:31:375 IST] 00000047 SystemOut O Error...:(
[2/25/12 22:56:31:371 IST] 00000047 SystemErr R java.lang.NullPointerException
[2/25/12 22:56:31:371 IST] 00000047 SystemErr R at plh.service.ejb.UserBean.getUserDetails(UserBean.java:41)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:45)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at java.lang.reflect.Method.invoke(Method.java:599)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at com.ibm.etools.utc.model.ReflectionMethodModel.invoke(ReflectionMethodModel.java:65)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at com.ibm.etools.utc.servlet.InvokeServlet.invoke(InvokeServlet.java:113)
[2/25/12 22:56:31:372 IST] 00000047 SystemErr R at com.ibm.etools.utc.servlet.InvokeServlet.doPost(InvokeServlet.java:374)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at javax.servlet.http.HttpServlet.service(HttpServlet.java:738)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at javax.servlet.http.HttpServlet.service(HttpServlet.java:831)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1443)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:790)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:443)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:175)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:91)
[2/25/12 22:56:31:373 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:859)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1557)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:173)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:455)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:384)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:83)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
[2/25/12 22:56:31:374 IST] 00000047 SystemErr R at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
[2/25/12 22:56:31:375 IST] 00000047 SystemErr R at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
[2/25/12 22:56:31:375 IST] 00000047 SystemErr R at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:202)
[2/25/12 22:56:31:375 IST] 00000047 SystemErr R at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:766)
[2/25/12 22:56:31:375 IST] 00000047 SystemErr R at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:896)
[2/25/12 22:56:31:375 IST] 00000047 SystemErr R at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1527)
Line no 41 in UserBean.java is :
//within UserBean.java, containing UserBean a stateless EJB
public class UserBean implements UserBeanInterface {
/**
* Default constructor.
*/
@PersistenceContext
private EntityManager manager;
public UserBean() {
}
public String authenticate(String name){
return null;
}
public String changePassword(){
return null;
}
public String setUserDetails(){
return null;
}
public String getUserDetails(){
System.out.println("hello");
try{
41=> Query query=manager.createQuery("from User");
List<User> results = query.getResultList();
if(results.size()!=0){
Iterator<User> stIterator=results.iterator();
while(stIterator.hasNext()){
User st=stIterator.next();
System.out.print("User Id:"+st.getUserId());
System.out.print("Type:"+st.getUserType());
System.out.print("Detail:"+st.getUserProfile());
}
}
else
{
System.out.println("Record not found.");
}
}
catch(Exception e)
{
e.printStackTrace();
System.out.println("Error...:(");
}
return "hi";
}
}
The User class, User has been generated automatically from the database tables. There is a USER table in the database. Please help on what the possible reason for this error could be.
Your
EntityManagermanageris no-interface an Enterprise Java Bean injected in your clientUserBean. EJBs should be injected in classes whose lifecycle is managed by the application server.The client must be either a web component or another enterprise bean. In your case, the client
UserBeanis a POJO (Plain Old Java Object). See here for further details about how to use EJBs.A possible simple solution is to make UserBean a Stateless Session Bean by adding the annotation javax.ejb.Stateless before the class definition. And you should eventually inject UserBean into your ManagedBean with the EJB annotation.