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unexpected exception

Asher Tarnopolski
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Joined: Jul 28, 2001
Posts: 260
hey folks, from time to time one of my servlets throws a nullpointerexception with this tree:

i can't understand from the exception message if this is a problem of code, but in any case the exception is thrown from time to time and not always...
yeh, the servlet runs on tomcat 4.0.


Asher Tarnopolski
SCJP,SCWCD
William Brogden
Author and all-around good cowpoke
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Joined: Mar 22, 2000
Posts: 12835
    
    5
What do you find when you look up line 673 in source code for the StandardWrapper class, org.apache.catalina.core package? That might give you a clue.
Bill
Bruce Jin
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Joined: Sep 20, 2001
Posts: 671
exam all the log files in logs folder you may find more useful debug info.


BJ - SCJP and SCWCD
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Asher Tarnopolski
Ranch Hand

Joined: Jul 28, 2001
Posts: 260
well, i'll take a look on the log files later. i can't see the 673 line of the source code. it's one of the tomcat classes, and i don't have the source code.
i found out that this exception is thrown if i recompile a servlet and try to run it again without restarting tomcat.
so, at least i know how to deal with it now
Bruce Jin
Ranch Hand

Joined: Sep 20, 2001
Posts: 671
i found out that this exception is thrown if i recompile a servlet and try to run it again without restarting tomcat

I suspect that your servlet uses other objects and does not handle objects creation properly. When a servlet is refreshed, other servlet/classes may also get destroyed.
Do you store objects in session?
Asher Tarnopolski
Ranch Hand

Joined: Jul 28, 2001
Posts: 260
yeh, it uses sessions and db connectivity, but as you see the exception is not thrown by a code
itself, but by tomcat...
in any case, in production noone will recompile the servlet , and for sure not when it's running.
William Brogden
Author and all-around good cowpoke
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Joined: Mar 22, 2000
Posts: 12835
    
    5
Well then - download the source code - its free and even fairly well annotated.
Bill
 
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