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From "Martin Gainty" <mgai...@hotmail.com>
Subject Re: How do I ........?
Date Wed, 15 Nov 2006 23:47:08 GMT
This is one of those SS!=DS discussions which means that variables placed/alloc'ed on the stack
are NOT the same as variables alloc'ed from heap
so 
when using a variable which is  alloced  on the stack AND initialised to some known value
(null) 
feel free to test that pre-allocated stack variable as with if(stack_variable == null)

If you dont know how this variable is alloc'ed or you know that the variable is alloc'ed from
heap use try / catch(NullPointerException npe)

to do otherwise you're risking your webapp causing 'an unhandled exception' when referencing
a unalloc'ed variable..

GL,
M-
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----- Original Message ----- 
From: "Steve R Burrus" <burrus1@swbell.net>
To: "Tomcat Users List" <users@tomcat.apache.org>
Sent: Wednesday, November 15, 2006 2:35 PM
Subject: Re: How do I ........?


> just a tiny correction for you Chris, and that is that the code ought to 
> be "if(in = = null)" not as u had it "if(null = = in)". Am I right or not?
> 
> Christopher Schultz wrote:
> 
>>-----BEGIN PGP SIGNED MESSAGE-----
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>>
>>Steve,
>>
>>Steve R Burrus wrote:
>>  
>>
>>>hi chris this is steve Burrus and the line of code in question is the
>>>while loop : "while( ( r = in.read(by)) != -1) {" the server error for a
>>>long time has always pointed to that line of code creating the NPE.
>>>    
>>>
>>
>>Yup, that's the first time you use the InputStream after attempting to
>>load your file. It's pretty simple to check for null: just use the code
>>I suggested in my last message:
>>
>>  
>>
>>>>Correct me if I'm wrong, but this generally checks for null:
>>>>
>>>>if(null == in)
>>>>  // handle the null condition
>>>>      
>>>>
>>
>>Now, it's up to you what you want to do in the event of a NULL image.
>>You could either return a "404 Not Found" error status, or return a
>>known good image that actually says "ERROR" on it.
>>
>>- -chris
>>
>>-----BEGIN PGP SIGNATURE-----
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>>
>>iD8DBQFFWM4Y9CaO5/Lv0PARArEgAKC8p+909qemHgpbGFmO5Fooh8AWcACeLF29
>>ajQlvN1B+YLbdmoKa+TFoyM=
>>=G5GE
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>>
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>>
>>  
>>
>
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