Methods for consideration:
Overhaul Validate class
Patch applied with change of name to isAssignableFrom.
Patch looks good. Does this match your thoughts Paul?
Should it be isAssignableFrom instead of isAssignable?
Attached patch with tests
Go with IllegalArgumentException. It was the parent class of IllegalClassException.
I have a problem with this one : I've done the isInstance and isAssignable, but I don't know which exception to throw...I was thinking about IllegalClassException, but it seems to have disappeared from LANG, so I think there's a good reason...Any help ?