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From Torsten Römer <>
Subject Re: Funny JAR file, WAS: Class.forName() gives NoClassDefFoundError
Date Wed, 08 Jun 2005 21:51:30 GMT

Jason Bainbridge schrieb:
> On 6/8/05, Torsten Römer <> wrote:
>>Just want to follow up on this.
>>Originally, the classes under /WEB-INF/classes were in a JAR file, which
>>I put in /WEB-INF/lib, but like this I always got NoClassDefFoundError.
>>So I thought there may be something wrong with the JAR file. I then
>>zipped the classes manually and replaced the JAR file with that. And see
>>there: No more NoClassDefFoundErrors.
>>The application JAR is, like the WAR file, created by an Ant task. It
>>can be opened/extracted without problems, but if I put it in Tomcat, I
>>always get NoClassDefFoundError. If I zip the classes manually, it works
>>just fine...
> Sounds more like a classloader/classpath problem, NoClassDefFoundError
> means it is finding multiple copies of the class.

Doesn't NoClassDefFoundError mean, that the class in question was 
present at compile time but is now missing at runtime?

> Are you setting your system classpath as well by any chance? If you
> are then you shouldn't be.

I don't, CLASSPATH is unset. I am pretty sure now, that the problem is 
the JAR file as created by the Ant task of the project's build.xml. If I 
just zip the classes manually, and use that instead of the JAR file, 
everything works just fine.

I will now check the JAR task, update Ant, build on another machine and 
so on to see if that makes any differences.


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