如何为不同类别的不同数据类型实现接口

Question

Say you have an interface which has a sum method, with two implementing classes A and B . Class A wants to sum two integers and class B wants to sum two long. What will be the implementation of interface C ?

class A implements C{
sum(2,3);
}

class B implements C {
sum(2.0,3.0);
}

How C should be implemented?

Answer 1

You can achieve this using a generic interface. For Example

    interface C<T extends Number> {
        T sum(T a, T b);
    }

    class A implements C<Long> {

        @Override
        public Long sum(Long a, Long b) {
            return a+b;
        }
    }

    class B implements C<Float> {

        @Override
        public Float sum(Float a, Float b) {
            return a+b;
        }
    }

Answer 2

A generic interface can help you here. You can extend the Number class using Generics in Java

Interface

public interface BaseInterface<T extends Number> {
    T sum(T a, T b);
}

Integer Implementation

public class ImplementationOne implements BaseInterface<Integer> {
    @Override
    public Integer sum(Integer a, Integer b) {
        return a + b;
    }
}

Double Implementation

public class ImpelementationTwo implements BaseInterface<Double> {
    @Override
    public Double sum(Double a, Double b) {
        return a + b;
    }
}