[Bluej-discuss] CheckStyle extension

[Davin McCall]

Stephen Edwards wrote:
> Universally in the checkstyle code base, everything uses
> Thread.currentThread().getContextClassLoader() to look up
> the appropriate class loader.
Hmm, my feeling is that this is the wrong thing to do. It should be 
expected that resources bundled as part of a library should be loadable 
by the same classloader as loaded the libraries classes, so surely it 
makes much more sense to use that same classloader. It's not guaranteed 
that the context classloader will be the same one. In fact it's fairly 
unclear when the context classloader *is* supposed to be used, but one 
good answer (for obvious reasons) is "when the current classloader 
(which loaded the current class) may not actually find the resource I am 
looking for". An example is RMI: the core RMI classes are generally 
going to be loaded by the system classloader, whereas they need to be 
able to find classes which are potentially loaded by a different 
classloader.

So, this sounds to me like a bug in Checkstyle - it shouldn't be using 
the context classloader. It should instead be doing 
"this.getClass().getClassLoader()" (or "Self.class.getClassLoader()", 
where "Self" is the name of the current class) to find an appropriate 
classloader.

If anyone is interested, there's an article here with more discussion 
about the use of current vs context class loaders:

http://www.javaworld.com/javaworld/javaqa/2003-06/01-qa-0606-load.html

Davin