ClassLoader.getSystemResourceAsStream(className) returning null when trying to load class file resource

Question

Class clazz = ...;
InputStream is = ClassLoader.getSystemResourceAsStream(clazz.getName().replace('.', '/') + ".class");

The input stream is returning null. I have used a simple java instrumentation agent to log classes as they are loaded and the class (clazz) is definitely being loaded by the ClassLoader. I've also tried

... Thread.currentThread().getContextClassLoader().getResourceAsStream(...));

and it returns null as well. What would be some possible causes for the resource not being able to be found by the class loader?

Answer 1

The Class has apparently been loaded by a different ClassLoader than the ones you're trying to find it with. Try this instead:

InputStream is = clazz.getClassLoader().getResourceAsStream(
    clazz.getName().replace('.', '/') + ".class");

Short of a flaw in the JVM, I don't think that can possibly return null.

Answer 2

Did you try getClass().getClassLoader().getResourceAsStream() Please make sure that the class file you tru to load in in classpath of your code. Also couild you please share the value of clazz.getName() ?

EDIT:

Are you doing something like following ?

Class clazz = Dummy.class;
InputStream is = ClassLoader.getSystemResourceAsStream(clazz.getName().replace('.', '/') + ".class");

I mean to say that do you define clazz as ClassName .class ? If not then try doing this and then see.