Question

基本上，我尝试使用switch但是当我运行它时，它没有做我制作的System.out.println。它编译没有问题。我不擅长编程，所以请解释一下你的答案。

import java.util.*;
public class MrCoffee {
    public static void main(String[] args) {
        String a;
        char d = 'y';
        Scanner mock = new Scanner(System.in);
        System.out.println("Hi, I am Mr.Coffee what is your name?");
        a = mock.nextLine();
        System.out.println("Thank you " + a + ".");
        System.out.println(a + ", do you have a validate rewards card currrently with you?");
        String b = ("y"), c = ("n");
        System.out.println("If yes enter the letter y. If no, please enter the letter n.");
        d = mock.next().charAt(0);
        if (d == 'y') {
            Scanner low = new Scanner(System.in);
            System.out.println("Ok, " + a + " please enter the amount of coffee you have bought today.");
            int coffeeam, none, one, two, three, value = 1, value2 = 4;
            coffeeam = low.nextInt();
            double total = coffeeam * 2.85;
            String start = ("Thank you Alexander, you will recieve"), rat = ("The total due amount is");
            none = coffeeam / 20;
            switch (none) {
            case 1:
                System.out.println("Unfortunately " + a + ", this is not enough to recieve any free coffee.");
                break;
            case 2:
                System.out.println("Unfortunately " + a + ", this is not enough to recieve any free coffee.");
                break;
            case 3:
                System.out.println("Unfortunately " + a + ", this is not enough to recieve any free coffee.");
                break;
            case 4:
                System.out.println("Unfortunately " + a + ", this is not enough to recieve any free coffee.");
                break;
            case 5:
                System.out.println(start + " 1 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 6:
                System.out.println(start + " 1 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 7:
                System.out.println(start + " 1 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 8:
                System.out.println(start + " 1 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 9:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 10:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 11:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 12:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 13:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 14:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 15:
                System.out.println(start + " 2 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 16:
                System.out.println(start + " 3 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 17:
                System.out.println(start + " 3 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 18:
                System.out.println(start + " 3 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 19:
                System.out.println(start + " 3 free coffee. " + rat + " " + total + " dollars.");
                break;
            case 20:
                System.out.println(start + " 3 free coffee. " + rat + " " + total + " dollars.");
                break;
            }
        } else if (d == 'n') {
            System.out.println("Sorry " + a + ", since you do not have a rewards card. I will not be able to decide on the number of free coffee you can get.");
            System.out.println("I would reccomend that you go to speak with one of our employees to register for a card.");
        }
    }
}

Answer 1

好的问题是因为你要用整数除以整数：

none = coffeeam / 20;

然后，如果玩家输入任何低于20的值，例如coffeeam = 19，则没有任何值为0，因为它将其四舍五入为0.因此，您的切换未运行，因为大部分时间都是无值我不知道为什么你把它除以20，但如果你能详细说明为什么除以20，我可以提供一个替代解决方案，以避免整数的舍入问题。

此外，我还想补充一点，你的开关看起来效率很低。如果您指定一个String变量并且只运行一个System.out.println方法，例如：

，则会更好

String message;
switch (variable) {
case 1:
  message = "Cat";
  break;
case 2:
  message = "Dog";
  break;
default:
  message = "None";
  break;
}
System.out.println(message);

Switch并没有按照指令行事

1 个答案: