Strange Illegal State Exception

Question

Hello all,
I've been writing a large webapp for a while and have suddenly started getting this exception. It turns up in the web server logs, occurs in the middle of a loop, and although all exceptions in my servlet are caught and forwarded to a generic error page, this exception causes the output to stop - leaving just the already-output HTML on the page. I guess this is because it's a runtime exception.
I know this can occur by calling getWriter() and getOutputStream() in the same servlet, but I've done nothing except println() on my PrintWriter after using getWriter() to retrieve it.
Anyone got any ideas on why this might occur?
Thanks!
Gemma

Answer 1

Here's the loop in which the error occurs:
           for(int i=0;i<theVector.size();i++)
          CustomObject temp = (CustomObject)theVector.elementAt(i);
          if(user.hasMultipleAttributes())
            if(i==0)
              out.println("<tr><td colspan=\"6\">For <b>" + temp.getCountry() + "</b></td></tr><tr><td colspan=\"6\"><br></td></tr>");
            else
              if(!temp.getCountry().equals(lastCountry))
                out.println("<tr><td colspan=\"6\">For <b>" + temp.getCountry() + "</b></td></tr><tr><td colspan=\"6\"><br></td></tr>");
            lastCountry = temp.getCountry();
          out.println("<tr><td>" + temp.getStory() + "</td>");
          out.println("<td>" + temp.getLanguage() + "</td>");
          if(currentUser.hasMultipleAttributes())
            out.println("<td>" + temp.getCountry() + "</td>");
          out.println("<td>" + temp.getRequestDate() + "</td>");
          out.println("<td>" + temp.getPublishDate() + "</td>");
          if(temp.isComplete())
            out.println("<td><img src=\"" + URLContainer.getTickImageURL() + "\"></img></td>");
          else
            out.println("<td><form method=\"post\" action=\"" + URLContainer.getCompleteStoryDetailsURL() + "\"><input type=\"hidden\" name=\"storyname\" value=\"" + temp.getStoryName() + "\"><input type=\"hidden\" name=\"language\" value=\"" + temp.getLanguage() + "\"><input type=\"hidden\" name=\"country\" value=\"" + temp.getCountry() + "\"><input type=\"submit\" value=\"Complete Usage Details\"></form></td>");
          out.println("</tr>");
          CustomObject temp2 = (CustomObject)theVector.elementAt(i+1);
          if(!lastCountry.equals(temp2.getCountry()))
            out.println("<tr><td colspan=\"6\"><br></td></tr>");
           } I can't see anything in here which would cause such an error. I don't pass the PrintWriter (out) anywhere... I don't set the buffer size and I don't believe that the PrintWriter is returned in autoFlush mode (not 100% sure though).
For redirects, I tend to use HttpServletResponse.sendRedirect().
Thanks
Gemma