How to write a method that takes two arguments of same type

Question

Hi,
I seldom do anything "advanced" in generics, but I've done my reading, and thought that I had an understanding of the basics, but I'm stuck on this. How do I write a method that takes two arguments that must be of exact same type.
I've tried something like:
public class GenericsTest1 {
    public static <T> void compare(T first, T second) {
}But the compare method can in this case be called with e.g.
String arg1 = null;
Long arg2 = null;
compare(arg1, arg2);I can restrict the call to something like GenericsTest1.<Long>compare(arg1, arg2), but I don't want to do it in the location that calls the method, and the method can still be invoked with subclasses of the specified type. E.g. this is valid (but I don't want it to be valid):
Number arg1 = null;
Long arg2 = null;
GenericsTest1.<Number>compare(arg1, arg2);So I then changed the method into something like this:
public class GenericsTest2 {
    public static <T, E extends T> void compare(T first, E second) {
}It feels like I'm half way there now. Compare can't be called with e.g:
Long arg1 = null;
Number arg2 = null;
compare(arg1, arg2);But this is still valid:
Number arg1 = null;
Long arg2 = null;
compare(arg1, arg2);Hmm... So what to do? I only want the method to be callable when arg1 and arg2 is of exact same type. Everything else should give a compilation error.
Kaj
Ps. No, I don't have a need for this, I'm just curious.

Answer 1

dannyyates wrote:
I haven't gone through everything you've written, but I would expect that in the first instance, it's inferred <T> to be Object. This is a good reason to parameterise the class rather than the method wherever that makes sense.Thanks for you reply, but as I said this isn't related to anything that I'm going to use. I just want to know if it ca ben done with a static method and generics.
Kaj