Question

I would like to perform an operation on two generics argument of the same type both extending Number.

Is it Possible?
I always used to call methods on generic arguments, but seems there is some problem using operators (The operator + is undefined for the argument type(s) T, T).

public static <T extends Number> T sum(T a, T b){
    return a+ b;
}

What am I doing wrong?

EDIT:
I try to improve a little bit my question. I understood that operators are not defined for type Number. It’s a bit sad this thing because it would be nice to perform such an operation without introducing new interfaces like suggested by @Victor Sorokin.

But I still don’t understand one thing: if operators are not implemented in the class Number, then at least in Double class should be implemented because I can use + operator with double.
Neither these line of code will compile:

public static <T extends Double> T sum(T a, T b){

    T c = a +b;
}

why?

Answer 1

It’s not possible because Number doesn’t have a + operator associated with it. In particular, you can’t do this:

Number a = new Integer(1);
Number b = new Integer(2);
Number c = a + b;