Servlet output problem

Question

hi
Im having a problem with reading some data out of my servlet textbox.
the user pastes some data into the textbox below and tixks the checkbox if
the first column is headings.
<BR><TEXTAREA NAME="Paste" ROWS="15" COLS="65"></TEXTAREA>
<ul>
<INPUT TYPE ="checkbox" NAME="firstcol" VALUE="First">First name is column name
//I save the parameters as below
          String table = request.getParameter("Paste");
          String firstcol=request.getParameter("firstcol");
               out.println(firstcol);
          session.setAttribute("table", table);
          session.setAttribute("firstcol", firstcol);
//then retrieve them
          String t= (String)session.getAttribute("table");
          String f= (String)session.getAttribute("firstcol");
          if(f.equals("First"))
          ColumnParser.column(t, writer);
          else //(f.equals(null))
          writer.println(t);
//the problem is it works fine if the user selects the checkbox and the column headings are printed out. But if the user doesnt select the checkbox, instead of the whole data being printed out I get an internal server error! I would be very grateful for any suggestions
thanks.           

Answer 1

The "internal server error" means that your code there threw an exception of some kind. You need to look into your servlet container's log files to find out exactly what it was -- there should be a stack trace in one of them. My bet is that you have a NullPointerException, since your code assumes that both parameters will be present in the request and does not check to see if either is null.