I'd start by getting the source for struts & scaffold. I'd then set a breakpoint in my debugger at the start of org.apache.struts.scaffold.ParameterAction.findSuccess() and step through until I found the NPE. I'd then look back up the call stack to try and figure out what happened.
Paul > -----Original Message----- > From: Caroline Jen [mailto:[EMAIL PROTECTED] > Sent: 20 May 2004 00:10 > To: [EMAIL PROTECTED] > Subject: Struggled for Days. Please Help With This > NullPointerException > Problem. > > > Please help me to find the possible place the problem > comes from. > > I have been struggling with this problem for days. I > tried a number of things but just could not get rid of > the problem. > > The Tomcat log does not give enough clue to trace > where the problem occurs. > My class extends Action. But the log keeps indicating > the problem is from > where the ParameterAction is. I am completely > disoriented. > > I think the Tomcat console provides better clue (log > messages are posted after the console messages): > > org.apache.struts.util.PropertyMessageResources <init> > > INFO: Initializing, > config='org.apache.struts.taglib.logic.LocalStrings', > returnNull=true > > org.apache.struts.util.PropertyMessageResources <init> > INFO: Initializing, > config='org.apache.struts.taglib.html.LocalStrings', > returnNull=true > > org.apache.struts.util.PropertyMessageResources <init> > INFO: Initializing, > config='org.apache.struts.util.LocalStrings', > returnNull=true > > org.apache.struts.util.PropertyMessageResources <init> > INFO: Initializing, > config='org.apache.struts.taglib.bean.LocalStrings', > returnNull=true > > WARNING: Unhandled Exception thrown: class > java.lang.NullPointerException > > Below are the log messages: > > ----- Root Cause ----- > java.lang.NullPointerException > at > org.apache.struts.scaffold.ParameterAction.findSuccess(Unknown > Source) > at > org.apache.struts.scaffold.BaseAction.execute(Unknown > Source) > at > org.apache.struts.action.RequestProcessor.processActionPerform > (RequestProcessor.java:484) > at > org.apache.struts.action.RequestProcessor.process(RequestProce > ssor.java:274) > ............. > ............. > > My struts-config.xml looks like: > [CODE] > <action > roles="administrator,editor,contributor" > path="/message/ListThreads" > type="org.apache.artimus.message.ListThread" > name="articleForm" > scope="request" > validate="false"> > <forward > name="success" > path="/signin/Welcome.jsp">; > </action> > [/CODE] > I have a java class ListThread.java that extends > Action. This java class simply calls a couple of > helper classes to access my database. In the end of > the ListThread.java, it is a standard statement: > > return ( mapping.findForward( "success" ) ); > > [CODE] > import LOTS OF PACKAGES AND CLASSES; > > public final class ListThread extends Action > { > public ActionForward execute(ActionMapping mapping, > ActionForm form, > HttpServletRequest > request, > HttpServletResponse > response) > throws Exception > { > > String memberName = request.getRemoteUser(); > > // for sort and order stuff > String sort = request.getParameter( "sort" ); > String order = request.getParameter( "order" ); > > if ( sort.length() == 0 ) sort = > "ThreadLastPostDate"; > if ( order.length()== 0 ) order = "DESC"; > > int offset = 0; > int rows = > MessageInboxConfig.ROWS_IN_THREADS; > offset = Integer.parseInt( request.getParameter( > "offset" ) ); > rows = Integer.parseInt( request.getParameter( > "rows" ) ); > > ListThreadHandler lthandler = new > ListThreadHandler(); > ListPostHandler lphandler = new > ListPostHandler(); > > int totalThreads = > lthandler.getNumberOfThreads_forReceiver( memberName > ); > if ( offset > totalThreads ) > { > throw new BadInputException( "The offset is > not allowed to be greater than total rows." ); > } > > Collection beans = > lthandler.getThreads_forReceiver_withSortSupport_limit( > memberName, offset, rows, sort, order ); > > SiteUtil.prepareNavigate( request, offset, > beans.size(), totalThreads, > MessageInboxConfig.ROWS_IN_THREADS ); > int totalPosts = > lphandler.getNumberOfPosts_forReceiver( memberName ); > > request.setAttribute( "ThreadBeans", beans ); > request.setAttribute( "TotalThreads", new > Integer( totalThreads ) ); > request.setAttribute( "TotalPosts", new Integer( > totalPosts ) ); > > return ( mapping.findForward( "success" ) ); > > } > } > [/CODE] > > > > > __________________________________ > Do you Yahoo!? > Yahoo! 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