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From Hunter Hillegas <hhille...@jacobstern.com>
Subject RE: Retrieving Objects from the Session Results in a Null Pointer
Date Tue, 15 Aug 2000 18:08:53 GMT
I see...

When using page session=true, is the object implicitly named session? Can I
change the name of the implicit object?


Hunter Hillegas, MCP
Web Engineer / System Administrator - Jacob Stern & Sons, Inc.
hhillegas@jacobstern.com
805-565-1411 PH * 805-565-8684 FAX

 -----Original Message-----
From: 	Steve Weiss [mailto:sweiss@aamc.org] 
Sent:	Tuesday, August 15, 2000 11:02 AM
To:	tomcat-user@jakarta.apache.org
Subject:	Re: Retrieving Objects from the Session Results in a Null
Pointer

Using the "page session" directive is not only better, it's required to
maintain session information between JSPs. When you do
request.getSession(true/false) inside your JSP, the session object you
get is only valid for that page, unless you declare that the JSP is
"playing sessions" with other JSPs. Once you've done that, you *still*
need to obtain a session object with request.getSession(), and the
boolean parameter says "create/don't create a new one" if one doesn't
already exist.

-S

Hunter Hillegas wrote:
> 
> I am sorta new to JSP. I've been doing servlets for quite some time...
> 
> I understand that there is a facility to automagically use a session on a
> page without declaring it:
> 
> <%@ page session="true" %>
> 
> instead of doing:
> 
> theSession = request.getSession(Boolean);
> 
> is declaring in the page a better approach?
> 
> As far as using the depreciated method, thanks for the heads up. I'll try
> that...
> 
> Hunter Hillegas, MCP
> Web Engineer / System Administrator - Jacob Stern & Sons, Inc.
> hhillegas@jacobstern.com
> 805-565-1411 PH * 805-565-8684 FAX
> 
>  -----Original Message-----
> From:   Steve Weiss [mailto:sweiss@aamc.org]
> Sent:   Tuesday, August 15, 2000 9:56 AM
> To:     tomcat-user@jakarta.apache.org
> Subject:        Re: Retrieving Objects from the Session Results in a Null
> Pointer
> 
> Two suggestions:
> 
> 1. You do have- <%@ page session="true" %> in your JSPs, yes? If not you
> won't be able to maintain session information from one page to another.
> 2. Use session.getAttribute() instead of session.getValue(), which is
> deprecated.
> 
> -Steve
> 
> Hunter Hillegas wrote:
> >
> > I have this code:
> >
> > <%
> > theSession = request.getSession(false);
> >
> > shoppingCart cart = null;
> >
> > try {
> >     cart = (shoppingCart)theSession.getValue("shoppingCart"); //This is
> > causing a null pointer exception. Arghhhh...
> > }
> > catch (Exception e) {
> >     e.printStackTrace();
> > }
> > %>
> >
> > that pulls an object out of the session...
> >
> > I can verify that the object is in the session. I can grab it from the
> page
> > I inserted it from with this code:
> >
> > shoppingCart testCart =
(shoppingCart)theSession.getValue("shoppingCart");
> >
> > I just can't get it from any other pages...
> >
> > Any ideas?
> >
> > Hunter Hillegas, MCP
> > Web Engineer / System Administrator - Jacob Stern & Sons, Inc.
> > hhillegas@jacobstern.com
> > 805-565-1411 PH * 805-565-8684 FAX
> 
> --
> Steve Weiss      Association of American Medical Colleges
> (202)828-0428    mailto:sweiss@aamc.org    http://www.aamc.org

-- 
Steve Weiss      Association of American Medical Colleges
(202)828-0428    mailto:sweiss@aamc.org    http://www.aamc.org

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