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another mock exam question

 
madhav changala
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Consider the following JSP code (See exhibit).What will it print for the very first request to this page as well as the web application that contains this page?

<html><body><% Integer count = (Integer) request.getSession(false).getAttribute("count"); if(count != null ) { out.println(count); } else request.getSession(false).setAttribute("count", new Integer(1));%>Hello!</body></html>

Select 1 correct option.
A.It will print Hello!
B.It will print Hello and will set the count attribute in the session.
C.It will throw a NullPointerException at request time.
D.It will not compile.


My answer was C.. as request.getSession(false) returns null at the very first request.. as null.set/getAttribute() results.. NullPointerexception.. right? But the answer given is B..

Could any help on this?

ThanksInAdvance

saivenumadhav

 
Joe San
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posted 17 years ago
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Even I guess that the answer is C!

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Srinivasan thoyyeti
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posted 17 years ago
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I will go for B. Why because by default session(Page Directive)=true is created for JSP.

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

 
Joe San
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Madhav, did you actually try this out??? I don't have a system to try it or otherwise I would have done it practically and checked!

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Paul Anilprem
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posted 17 years ago
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Hi Madhav,
Did you see the detailed explanation that is provided with it?

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Manju Devarla
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it prints Hello! no Nullpointer exception
 
achayya matta
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Yes, it prints hello for the first request and "1 hello" for the next request.
 
madhav changala
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I did n't try out this one..

But there was no detailed answer...

Could any one from above tell how hello will be the correct answer?

ThanksInadvance

saivenumadhav

 
Rishi Chopra
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posted 17 years ago
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hi,

Since the question has not specified the page directive in the code snippet .. so the jsp container assumes that the page directive has session set to true.So a jsp page automatically participates in session tracking.
when
<% Integer count = (Integer) request.getSession(false).getAttribute("count");
is encounteres then the session is already there so "request.getSession(false)" wud return the session created implicitly by the page but there is no attribute named count so above statement is equal to Integer count=null;

then the code enters the else clause where the count is set as an attribute with value as new Integer(1) and then Hello is printed..

I hope i am able to clear your confusion

Regards
Rishi Chopra

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Niranjan Deshpande
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posted 17 years ago
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yes rishi you are...

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