wood burning stoves 2.0*
The moose likes Web Component Certification (SCWCD/OCPJWCD) and the fly likes Request Attribute confusion Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login


JavaRanch » Java Forums » Certification » Web Component Certification (SCWCD/OCPJWCD)
Bookmark "Request Attribute confusion" Watch "Request Attribute confusion" New topic
Author

Request Attribute confusion

Joe Harry
Ranch Hand

Joined: Sep 26, 2006
Posts: 9395
    
    2

Guys,

I tried the following,

My test.jsp,


But if I comment Line 1, I'm getting a null pointer?? I know the request.getAttribute("jothi") in the System.out.println(request.getAttribute("jothi")) gets a call to toString90 method but why the other throws a null pointer??


SCJP 1.4, SCWCD 1.4 - Hints for you, Certified Scrum Master
Did a rm -R / to find out that I lost my entire Linux installation!
Srinivasan thoyyeti
Ranch Hand

Joined: Feb 15, 2007
Posts: 557
Hi Jyothi,


When you first request the jsp file

1. jsp converted to servlet and in service attribute jyothi placed.
2. and in response html form sent.
3. your request ends here.(that means your request,response objects gone).


secondly when user submits the form

1. control reaches servlet
2. tries to find jyothi in request scope.
finally gives up return null.

[ May 11, 2007: Message edited by: Srinivasan thoyyeti ]

Thanks & Regards, T.Srinivasan
SCWCD 1.4(89%), SCJP 5.0(75%)
Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14688
    
  16

Try the following :


You are using a java1.5 feature called unboxing, which converts an Integer into an int.
But you are trying to convert null into an int, which fails.
It would work with Integer i = (Integer)request.getAttribute("jothi");

Maybe you'd better use SDK1.4 to practice for this exam.


[My Blog]
All roads lead to JavaRanch
Joe Harry
Ranch Hand

Joined: Sep 26, 2006
Posts: 9395
    
    2

Satou,

You are really amazing. No words to praise you man. You point out my mistakes elegantly. Thanks!
Joe Harry
Ranch Hand

Joined: Sep 26, 2006
Posts: 9395
    
    2

Consider the code as below,



I'm confused as when I run this I'm getting shanar as the o/p. Shouldn't the forward call in includedjsp.jsp ignore anything that we set???

 
GeeCON Prague 2014
 
subject: Request Attribute confusion