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From Andrej Rosenheinrich <tom...@die-titanen.de>
Subject NullPointerException in AdaptiveClassLoader
Date Fri, 31 Aug 2001 15:37:22 GMT
Hello,

I posted this question once in the user-list, but got no reply. After 
getting no help and starting to look at the sourcecode this thing gets 
even more weird to me, so I hope you excuse that I now post it to the 
dev-list.

I broke down my question to a simple example. I have a html-page, 
calling a servlet and submitting one parameter. Calling this servlet I 
am getting:

Error: 500
Location: /aba2/test
Internal Servlet Error:
java.lang.NullPointerException at 
org.apache.tomcat.loader.AdaptiveClassLoader.loadClass 
(AdaptiveClassLoader.java:471) (pc 145) at 
org.apache.tomcat.loader.AdaptiveServletLoader.loadClass 
(AdaptiveServletLoader.java:174) (pc 18) at 
org.apache.tomcat.core.ServletWrapper.loadServlet 
(ServletWrapper.java:265) (pc 38) at 
org.apache.tomcat.core.ServletWrapper.init (ServletWrapper.java:289) (pc 
33) at org.apache.tomcat.core.Handler.service (Handler.java:254) (pc 19) 
at org.apache.tomcat.core.ServletWrapper.service 
(ServletWrapper.java:372) (pc 140) at 
org.apache.tomcat.core.ContextManager.internalService 
(ContextManager.java:797) (pc 250) at 
org.apache.tomcat.core.ContextManager.service (ContextManager.java:743) 
(pc 3) at 
org.apache.tomcat.service.http.HttpConnectionHandler.processConnection 
(HttpConnectionHandler.java:210) (pc 388) at 
org.apache.tomcat.service.TcpWorkerThread.runIt 
(PoolTcpEndpoint.java:416) (pc 73) at 
org.apache.tomcat.util.ThreadPool$ControlRunnable.run 
(ThreadPool.java:498) (pc 132) at java.lang.Thread.run (Thread.java:484) 
(pc 11)

My servlet, the html-file, the web.xml file and server.xml-file are 
attached.

After having no idea at all what's going on I took a look at the 
sourcecode. First, I am using tomcat 3.2.1 under OpenVMS. Unfortunatly I 
couldnt get the code for version 3.2.1, only for 3.2.3. So I have to 
assume that the code for this class didnt change (did it?). Looking at 
the method loadClass in AdaptiveClassLoader I actually dont see a 
possible source for a NullPointerException. There can be a result value 
null, but nowhere a NullPointerException is thrown, as far as I looked 
at the statements in this method.

My questions: what can cause such an exception? did the class 
AdaptiveClassLoader change from 3.2.1 to 3.2.3? where is the point this 
exception is thrown?
Another question, under OpenVMS I have my doubts that an errormessage 
OutOfError is necessarily related to memory. What else can cause such an 
error? Bufferlimits? Processlimits? Is it possible/planned to give more 
specific errormessages? Is it possible to get involved in this project 
somehow?

Hope to not disturb anyone

Greetings, TIA
Andrej Rosenheinrich

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