Need help with NullPointerException in my servlet
Hi guys , I have a servlet called submit servlet ,which instantiates a DataAccessObject called LetterRequestDAO and stores a letter using that.
Here is the part of my code that does that.
letterList =null;
LtrDAO =new LetterRequestDAO("001");
LtrDAO.storeLetter(EID);
letterList = LtrDAO.getLetterList();
I have imported the package that LetterrequestDAO belongs to using
import com.letterrequest.DAOs.LetterRequestDAO;
I checked the LetterrequestDAO (I inserted a main method in it and ran it)and its not throwing any null pointerException .Its storing the Letter and retreiving the ArrayList with no problem .
The program highlights at
LtrDAO.storeLetter(EID); when the null pointer exception is thrown .What could be the problem ?Why is my servlet not able to instantiate LetterrequestDAO ?Any ideas .I'm stuck with this problem for a week now.I really appreciate any suggestions .
I can post the two programs if it wont annoy anyone .
Thanks a bunch ,
Kavita
[1176 byte] By [
KRiveraa] at [2007-10-2 11:47:56]
If the servlet can't instantiate your variable, you'll get either a ClassNotFoundException or an OutOfMemoryException. So that's not the problem.
The problem is most likely inside the storeLetter() method, the method is throwing a NullPointerException. The logical first suggestion would be: is the EID parameter null by any chance?
hi ,
No the EmpID is not null .
In the message , you will see that EmployeeID is 5.My connection object is not instantiating .Like I said I am getting the connection perfectly fine from LetterRequestDAO class.I dunno what's wrong.
Below is the error I get .
Kavita
[2/9/06 11:13:52:777 EST] 53d1373d WebGroupI SRVE0180I: [LTRWEB] [/LTRWEB] [Servlet.LOG]: SubmitServlet: init
[2/9/06 11:13:52:817 EST] 53d1373d SystemOutO Employee ID in else part of submit servlet is 5
[2/9/06 11:13:52:877 EST] 53d1373d SystemOutO Connection madenull
[2/9/06 11:13:52:877 EST] 53d1373d SystemOutO LtrDAO is instantiated
[2/9/06 11:13:52:877 EST] 53d1373d SystemOutO In storeLetter -in try block before setting String qs
[2/9/06 11:13:52:877 EST] 53d1373d SystemOutO In storeLetter -in try block after setting String qs
[2/9/06 11:13:52:877 EST] 53d1373d SystemOutO connection in LetterRequestDAO is null
[2/9/06 11:13:53:327 EST] 53d1373d WebGroupE SRVE0026E: [Servlet Error]-[SubmitServlet]: java.lang.NullPointerException
at com.letterrequest.DAOs.LetterRequestDAO.storeLetter(LetterRequestDAO.java:39)
at com.letterrequest.servlets.SubmitServlet.doPost(SubmitServlet.java:50)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at com.ibm.ws.webcontainer.servlet.StrictServletInstance.doService(StrictServletInstance.java:110)
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet._service(StrictLifecycleServlet.java:174)
at com.ibm.ws.webcontainer.servlet.IdleServletState.service(StrictLifecycleServlet.java:313)
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet.service(StrictLifecycleServlet.java:116)
at com.ibm.ws.webcontainer.servlet.ServletInstance.service(ServletInstance.java:283)
at com.ibm.ws.webcontainer.servlet.ValidServletReferenceState.dispatch(ValidServletReferenceState.java:42)
at com.ibm.ws.webcontainer.servlet.ServletInstanceReference.dispatch(ServletInstanceReference.java:40)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.handleWebAppDispatch(WebAppRequestDispatcher.java:1019)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:592)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:204)
at com.ibm.ws.webcontainer.srt.WebAppInvoker.doForward(WebAppInvoker.java:125)
at com.ibm.ws.webcontainer.srt.WebAppInvoker.handleInvocationHook(WebAppInvoker.java:286)
at com.ibm.ws.webcontainer.cache.invocation.CachedInvocation.handleInvocation(CachedInvocation.java:71)
at com.ibm.ws.webcontainer.srp.ServletRequestProcessor.dispatchByURI(ServletRequestProcessor.java:182)
at com.ibm.ws.webcontainer.oselistener.OSEListenerDispatcher.service(OSEListener.java:334)
at com.ibm.ws.webcontainer.http.HttpConnection.handleRequest(HttpConnection.java:56)
at com.ibm.ws.http.HttpConnection.readAndHandleRequest(HttpConnection.java:615)
at com.ibm.ws.http.HttpConnection.run(HttpConnection.java:439)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:912)
> at com.letterrequest.DAOs.LetterRequestDAO.storeLetter
> (LetterRequestDAO.java:39)
This means that a NullPointerException occurs inside the method LetterRequestDAO.storeLetter(), in file LetterRequestDAO.java on line 39.
Look at that line and figure out what is null on that line. It is either a null array in array access (nullArray[42]), member variable access (nullObject.ni = 7) or method call (nullObject.foo()).
In my LetterRequestDAO constructor I am instantiating a Connection Factory.
public LetterRequestDAO(String ID)
{
ConnectionFactory cFactory = new ConnectionFactory();
this.con = cFactory.getConnection(ID);
System.out.println("Connection made"+ con);
}
This is instantiating and getting me the connection , if I insert a main() into LetterRequestDAO itself .
But if I am instantiating LetterRequestDAO from SumbitServlet
LtrDAO = new LetterRequestDAO("001");
if(LtrDAO!=null)
{
System.out.println("LtrDAO is instantiated");
}
LtrDAO.storeLetter(EID);
letterList = LtrDAO.getLetterList();
if (letterList != null)
{
HttpSession session = req.getSession(true);
req.setAttribute("LTRList", letterList);
session.setAttribute("LtrList", letterList);
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher(
"LetterRequestJSP.jsp");
for some reason I am not able to get Connection
That's why my program is failing at pst = con.prepareCall(qs); in storeLetter method .Ipublic void storeLetter(String EID)
{
try
{PreparedStatement pst = null;
System.out.println(
"In storeLetter -in try block before setting String qs");
String qs = "insert into LetterRequest(EmpID) values(?)";
System.out.println(
"In storeLetter -in try block after setting String qs");
System.out.println("connection in LetterRequestDAO is "+ con);
[b]pst = con.prepareCall(qs);[/b]
pst.setString(1, EID.trim());
System.out.println(
"In storeLetter -in try block after prepareCall");
boolean b = pst.execute();
System.out.println("After execute");
}
I am not able to understand WHY I am not able to get a connection from SubmitServlet . when I am able to get connection from other programs Any ideas please?
Thanks,
kavita
