I am trying to connect to a database in Action Class and set return data into a vector. Then vector is set into session and session is read from forwarded page. However, I am getting NullPointerException. Now I put the part of the code that I think might generate an exception into try block, but no luck same exception. In addition, stack trace does not seem to give the line of perform() where error occurs.

SEVERE: Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at app.ExecuteQueryAction.perform(Unknown Source)
at org.apache.struts.action.ActionServlet.processActionPerform(ActionServlet.java:1787)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1586)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:510)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:825)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:731)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:526)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)


and Action Class:

package app;

import java.io.IOException;
import java.util.Vector;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionServlet;
import com.kwi.DBDriver;

public final class ExecuteQueryAction extends Action {

   public ActionForward perform(ActionMapping mapping,
           ActionForm form,
           HttpServletRequest request,
           HttpServletResponse response)
       throws IOException, ServletException {

       // Obtain username and password from web tier
       String sqlQuery = ((ExecuteQueryForm) form).getSQLQuery();
       Vector v = new Vector();
       HttpSession session = request.getSession();
       try{
               v = DBDriver.doSelect("generic2",sqlQuery);
               v.add("test");
               session.setAttribute("output",v);
       }
       catch(NullPointerException nle){
               v.add("no good");
               session.setAttribute("output",v);
       }
       session.setAttribute("query",form);

       // Return success
       return mapping.findForward("success");

   }

} // End LogonAction

thanks,
Alex


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