Is it possible to write a generic +1 method for numeric box types in Java?

Question

This is NOT homework.

Part 1

Is it possible to write a generic method, something like this:

Answer 1

FWIW this isn't really a limitation of generics.

The + operator only works on primitives. The reason it works for Integer or Long is because of autoboxing/unboxing with their primitive types. Not all Number subclasses have a matching primitive type, but more importantly Number doesn't have a matching primitive type. So taking generics out of it completely, the following code would still be wrong:

public Number plusOne(Number num) {
    return num + 1;
}