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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 20:55:34 GMT
I've made some progress now...

I no longer get a null pointer but the cart object I retrieve is getting
pulled in from the session as a null value...

This code:

shoppingCart cart = (shoppingCart)session.getAttribute("shoppingCart");

is pulling it in and then I check to see if (cart != null) and it is always
coming up as null...

This is in contrast to the preceding page where the cart can be retrieved
and is not null.


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 1:21 PM
To:	tomcat-user@jakarta.apache.org
Subject:	Re: Retrieving Objects from the Session Results in a Null
Pointer

Try replacing putValue(String, Object) with setAttribute(String, Object)

Also try printing out the value from session.getId() in both JSPs to see
if it's the same.

Hunter Hillegas wrote:
> 
> Sure...
> 
> Here is the code from index.jsp that creates and stores the cart:
> 
> shoppingCart cart = new shoppingCart();
> cartItem item = new cartItem("1", "family", "description", "uom", "spec",
> "sellprice", "1");
> cart.addItem(item);
> session.putValue("shoppingCart", cart);
> 
> Here is the code from another page that also is page session=true that
tries
> to read the cart...
> 
> shoppingCart cart = null;
> cart = (shoppingCart)session.getAttribute("shoppingCart"); //This is
causing
> a null pointer exception. Arghhhh...
> 
> Any ideas?
> 
> 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 12:07 PM
> To:     tomcat-user@jakarta.apache.org
> Subject:        Re: Retrieving Objects from the Session Results in a Null
> Pointer
> 
> Can you post some of your code?
> 
> Hunter Hillegas wrote:
> >
> > After converting my code to use implicit sessions, I still get the same
> null
> > pointer. Any other ideas?
> >
> > 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
> 
> --
> 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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