• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Ron McLeod
  • Paul Clapham
  • Bear Bibeault
  • Junilu Lacar
Sheriffs:
  • Jeanne Boyarsky
  • Tim Cooke
  • Henry Wong
Saloon Keepers:
  • Tim Moores
  • Stephan van Hulst
  • Tim Holloway
  • salvin francis
  • Frits Walraven
Bartenders:
  • Scott Selikoff
  • Piet Souris
  • Carey Brown

<jsp:useBean> unexpected behavior

 
Ranch Hand
Posts: 34
Eclipse IDE MySQL Database Java
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
In servlet if we have


jsp code :


In the generated servlet:


Runtime exception is thrown



and in case we have something apart from null in the request attribute:


the generated servlet has:


Why the null condition has diffeent behaviour in both cases in the generated servlet?
 
Ranch Hand
Posts: 35
Spring Java Linux
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Whooaah! Very strange.

From what I have learnt, I think the generated servlet for a given jsp should be the same irrespective of what some other servlet does before calling it.

Could someone please clarify.

ps: which container are you using?
 
Ranch Hand
Posts: 437
Oracle Java
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi, Shwetha.

Can you please post, how you are accessing jsp:useBean in the above case?
 
Shwetha Sharma
Ranch Hand
Posts: 34
Eclipse IDE MySQL Database Java
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I missed the difference in usage.

If we dont specify the class attribute for the jsp:use bean, then Instanciation Exception is thrown in case the bean is not present in session or its null




results in



and in case we give class attribute


results in


 
Ranch Hand
Posts: 2874
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
From the syntax ref:

The <jsp:useBean> element locates or instantiates a JavaBeans component. <jsp:useBean> first attempts to locate an instance of the Bean. If the Bean does not exist, <jsp:useBean> instantiates it from a class or serialized template.

 
I have gone to look for myself. If I should return before I get back, keep me here with this tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop
https://coderanch.com/wiki/718759/books/Building-World-Backyard-Paul-Wheaton
    Bookmark Topic Watch Topic
  • New Topic