表达动态多态性

Question

根据用户输入的动物危险等级，calculate_insurance方法选择正确的案例，并进行计算，确定动物保险的成本。在父类中设置危险等级，在具有动态多态性的两个子类中通过重写父类进行保险计算。解决这个问题的最好方法是什么？非常感谢用您的代码进行解释。

基类-

public abstract class Animal
{
        protected int danger_rating = 0;

          //get danger rating from user (1-5)
        while (true)
        {
            Console.WriteLine("What is the animals danger rating? \nSelect a number between 1 - 5: "); //Prompt user to type in animals danger rating
            string input = Console.ReadLine(); //reads string input 

            if (int.TryParse(input, out danger_rating)) //convert user string input to int danger_rating
            {
                if (danger_rating == 1) //loop until danger_rating is between 1 and 5
                {
                    break;
                }
                else if (danger_rating == 2)
                {
                    break;
                }
                else if (danger_rating == 3)
                {
                    break;
                }
                else if (danger_rating == 4)
                {
                    break;
                }
                else if (danger_rating == 5)
                {
                    break;
                }
                else
                {
                    Console.WriteLine("Invalid Number. \nNumber must be between 1 - 5");
                }
            }
            else
            {
                Console.WriteLine("This is not a number");
            }

        public virtual double calculate_insurance(int danger_rating)
        {
            return 0;
        } 
}

哺乳动物类-

public class Mammal : Animal //Derived class
{
        public virtual double calculate_insurance(int danger_rating)
        {
            int ins_base = 5000; //base for mammals
            
            double Insurance; //this will contain the output

            //Select case based on danger rating 1 - 5
            switch (danger_rating)
            {
                case 1:
                    Insurance = (ins_base * 10) * 0.02;
                    break;

                case 2:
                    Insurance = (ins_base * 20) * 0.05;
                    break;

                case 3:
                    Insurance = (ins_base * 30) * 0.05;
                    break;

                case 4:
                    Insurance = (ins_base * 40) * 0.05;
                    break;

                case 5:

                    Insurance = (ins_base * 50) * 0.10;
                    break;

                default:
                    Console.WriteLine("Invalid danger rating");
                    break;

            } //end of switch

            return base.calculate_insurance(danger_rating);

        }
}

爬行动物类-

public class Reptile : Animal //Derived class
{
        public virtual double calculate_insurance(int danger_rating)
        {
            int ins_base = 1000; //base for reptiles
            
            double Insurance; //this will contain the output

            //Select case based on danger rating 1 - 5
            switch (danger_rating)
            {
                case 1:
                    Insurance = (ins_base * 10) * 0.02;
                    break;

                case 2:
                    Insurance = (ins_base * 20) * 0.05;
                    break;

                case 3:
                    Insurance = (ins_base * 30) * 0.05;
                    break;

                case 4:
                    Insurance = (ins_base * 40) * 0.05;
                    break;

                case 5:
                    Insurance = (ins_base * 50) * 0.10;
                    break;

                default:
                    Console.WriteLine("Invalid danger rating");
                    break;

            } //end of switch

            return base.calculate_insurance(danger_rating);

        }
}

Answer 1

我不确定是否存在需要“解决”的问题，除了which循环的基类中的语法错误(在方法级别上浮动)和计算派生类型的一些保险值但随后返回基类型的保险值(即0)的一些繁琐之处。

哺乳动物和爬行动物中的calculate_insurance方法应该声明给override基本方法，并且应该以return Insurance结尾(注意:它应该被称为insurance；我们在PascalCase中不命名局部变量)，不返回调用基的结果。

如果你想知道如何使用你所创造的东西。这种性质的多态背后的想法是，您可以有一个基本类型的变量，而不知道或不关心实际类型存储在其中，因为您只使用基本类型声明存在的功能

Animal a = new Mammal();
a.calculate_insurance(1);  //returns 1000, the rating for a Mammal of type 1

Animal b = new Reptile();
b.calculate_insurance(1);  //returns 200, the rating for a Reptile of type 1