Bytebuddy - subclass a final class

Question

I'm trying to write a generic method that looks like this:

private static <T> Class<? extends T> immutableVersionOfClass(Class<T> clazz) {
    return new ByteBuddy()
            .subclass(clazz)
            .method(not(returns(VOID)))
            .intercept(to(GetterInterceptor.class))
            .method(returns(VOID))
            .intercept(to(SetterInterceptor.class))
            .make()
            .load(clazz.getClassLoader())
            .getLoaded();
}

but when final class is passed as an argument I get an exception: java.lang.IllegalArgumentException: Cannot subclass primitive, array or final types I'd like my method to be able to subclass also final classes. Is there any workaround for this problem?

Answer 1

There is no way to subclass a final class. It's forbidden by the language spec .

ByteBuddy largely respects the language specification, so even if you wanted to extend a final class, you couldn't unless you were able to manipulate the byte code of the class you wanted to override to be not final , although at that point you're messing with things you really shouldn't be.