I cannot for the life of me find a definition of what the Java VM flag CMSClassUnloadingEnabled actually does, other than some very fuzzy high-level definitions such as “gets rid of your PermGen problems” (which it doesn’t, btw). I have looked on Sun’s/Oracle’s site, and even the options list doesn’t actually say what it does. … Read more
Does anyone know how to programmaticly find out where the java classloader actually loads the class from? I often work on large projects where the classpath gets very long and manual searching is not really an option. I recently had a problem where the classloader was loading an incorrect version of a class because it … Read more
In Java, you can load all kinds of resources using the same API but with different URL protocols: file:///tmp.txt http://127.0.0.1:8080/a.properties jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class This nicely decouples the actual loading of the resource from the application that needs the resource, and since a URL is just a String, resource loading is also very easily configurable. Is there a … Read more
I wonder what the difference is between Class.getResource() and ClassLoader.getResource()? edit: I especially want to know if any caching is involved on file/directory level. As in “are directory listings cached in the Class version?” AFAIK the following should essentially do the same, but they are not: getClass().getResource() getClass().getClassLoader().getResource() I discovered this when fiddling with some … Read more
What is the difference between a thread’s context class loader and a normal class loader? That is, if Thread.currentThread().getContextClassLoader() and getClass().getClassLoader() return different class loader objects, which one will be used? 4 Answers 4
How do I search the whole classpath for an annotated class? I’m doing a library and I want to allow the users to annotate their classes, so when the Web application starts I need to scan the whole classpath for certain annotation. I’m thinking about something like the new functionality for Java EE 5 Web … Read more
Why is it so hard to do this in Java? If you want to have any kind of module system you need to be able to load JAR files dynamically. I’m told there’s a way of doing it by writing your own ClassLoader, but that’s a lot of work for something that should (in my … Read more
In my office, the mere mention of the word Xerces is enough to incite murderous rage from developers. A cursory glance at the other Xerces questions on SO seem to indicate that almost all Maven users are “touched” by this problem at some point. Unfortunately, understanding the problem requires a bit of knowledge about the … Read more
