Because hs is null.

-- 
Tim Moore / Blackboard Inc. / Software Engineer
1899 L Street, NW / 5th Floor / Washington, DC 20036
Phone 202-463-4860 ext. 258 / Fax 202-463-4863


> -----Original Message-----
> From: Mufaddal [mailto:[EMAIL PROTECTED]] 
> Sent: Friday, February 14, 2003 2:35 AM
> To: Tomcat List
> Subject: Servlet produces HTML .. how do i pass attributes in 
> the session object ?
> 
> 
> Hi ...
> 
> in my doPost() I do some processing and then I do ....
> 
>              HashSet hs = getFruits(userName);
> 
>              PrintWriter ot = response.getWriter();
>              ot.println("<html>");
>              ot.println("<body>");
>              ot.println("<h1><b> I AM FROM TIMBAKTU </b></h1>");
>              ot.println("</body>");
>              ot.println("</html>");
> 
>              session.setAttribute("FRUITS", hs);
>              ot.close();
> 
> Basically my servlet is writing some HTML output and setting 
> a HashSet  
> in the session object. When I do this i get the following 
> exception : Internal Servlet Error:
> 
> java.lang.NullPointerException
>       at java.util.Hashtable.put(Hashtable.java:389)
>       at  
> org.apache.tomcat.session.StandardSession.setAttribute(Standar
> dSession.j 
> ava:731)
>       at  
> com.wavesinmotion.cw.classes.jsphelpers.LoginServlet.doPost(Lo
> ginServlet 
> .java:61)
>       at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
>       at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
>       at  
> org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper
> .java:405)
>       at org.apache.tomcat.core.Handler.service(Handler.java:287)
>       at  
> org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
>       at  
> org.apache.tomcat.core.ContextManager.internalService(ContextM
> anager.jav 
> a:806)
>       at  
> org.apache.tomcat.core.ContextManager.service(ContextManager.java:752)
>       at  
> org.apache.tomcat.service.http.HttpConnectionHandler.processCo
> nnection(H 
> ttpConnectionHandler.java:213)
>       at  
> org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoin
> t.java:416 
> )
>       at  
> org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPo
> ol.java:50 
> 1)
>       at java.lang.Thread.run(Thread.java:554)
> 
> Does anybody know why ?
> 
> Thanks.
> 

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