Working around unchecked conversions when using reflection

Question

I think I've convinced myself that there's no way around this issue when using reflection and Generics, but here's the issue:
Suppose I've got a method that uses reflection to compare an arbitrary property in
an arbitrary pair of beans (of the same class).
public static <T> int compare(T bean0, T bean1, String prop) throws Exception {
     Method m = bean0.getClass().getMethod(
               "get" + prop.substring(0,1).toUpperCase() +
               prop.substring(1));
     Object o0 = m.invoke(bean0);
     Object o1 = m.invoke(bean1);
     if (o0 instanceof Comparable &&
         o1 instanceof Comparable &&
         (o1.getClass().isAssignableFrom(o0.getClass()) ||
          o0.getClass().isAssignableFrom(o1.getClass()))) {
          return ((Comparable)o0).compareTo(o1); // compiler warning
     } else {
          return o0.toString().compareTo(o1.toString());
}There's no way that, in general, when using reflection to invoke methods, that you can coerce the types to avoid compile-time type safety warnings. I think the above code is guarranteed not to throw a runtime ClassCastException, but there's no way to write the code so that the compiler can guarrantee it. At least that's what I think. Am I wrong?

Answer 1

Ok it looks like you're dealing with a classloader issue. when you call that method, it is the equivelant of calling
Class.forName("Box", true, this.getClass().getClassLoader())The exception is thrown when your class's classloader cannot find the class box. try putting 'null' there
Class.forName("Box", true, null)and it will request the bootstrap classloader to load the class. just make sure you have permission :
If the loader is null, and a security manager is present, and the caller's class loader is not null, then this method calls the security manager's checkPermission method with a RuntimePermission("getClassLoader") permission to ensure it's ok to access the bootstrap class loader. (copied from the API)