Java中不同参数数据类型的继承和重载方法

When I was analyzing a simple java code related with overloading and inheritance I expected to recieve an output that overloads matching the argument's data types. But it doesn't work that way.

代码:

class A {
        public int calc (double num){
            System.out.println("calc A");
            return (int)(num+1);}
    }
class B extends A{
        public int calc (long num){
            System.out.println("calc B");
            return (int)(num+2);}
    }
class C extends B{
        public int calc (int num){
            System.out.println("calc C");
            return num+3;}
    }
class D extends C{
        public int calc (float num){
            System.out.println("calc D");
            return (int)(num+4);}
    }

class Program{
        public static void main(String[] args){
            int num1=10;
            long num2 = num1;

            Object o1 = num1;
            System.out.println("num1 Type: "+o1.getClass().getName());

            Object o2 = num2;
            System.out.println("num2 Type: "+o2.getClass().getName());

            A a1=new D();
            A a2=new D();

            System.out.println("a1 Type: "+a1.getClass().getName());
            System.out.println("a2 Type: "+a2.getClass().getName());

            int result = a1.calc(num1)+a2.calc(num2);
            System.out.println("Number: "+result);
        }
    }

输出:

num1 Type: java.lang.Integer
num2 Type: java.lang.Long
a1 Type: D
a2 Type: D
calc A
calc A
Number: 22

我在这里测试代码:ideone

推荐答案

您的主要问题似乎是关于为什么类型输出与正式类型不匹配.这完全是故意的，这也是面向对象编程如此强大的原因.