I guess the only plase where NPE may occure is the line:
String sqlQuery = ((ExecuteQueryForm) form).getSQLQuery();
Are you sure there's a form definition available for this action?
It means, is there a "name" attribute defined in an appropriate <action>
element in your struts-config.xml?
Pavel
On Wed, 19 Jan 2005 12:34:51 -0500, Alex Kravets
<[EMAIL PROTECTED]> wrote:
> 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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