Question

一切都很好。但当它到达目的地并询问我是否想再试一次它只是终止程序，我没有输入y或n

编辑：对不起，我应该在发布前更好地查看预览，但似乎在提交时搞砸了代码。这是我的实际代码

import java.util.Scanner;

class MillionDollarYears2
{
public static void main(String[] args)
{
    String answer = "y";
    double dollars;
    final double interest = 0.05;
    int year = 0;
    Scanner scan = new Scanner(System.in);

    while(answer.equals("y") )
    {
        System.out.println("How many dollars are deposited?");
        dollars = scan.nextDouble();


        while(dollars < 1000000.00)
        {
            dollars = dollars + dollars * interest;
            year = year + 1;
        }
           System.out.println("It took " + year + " years to reach your goal.");

           System.out.println("Would you like to try again? (y or n)");
           answer = scan.nextLine();


    }

}

}

Answer 1

您没有输入正确变量的y / n答案。您的相关摘要（带有澄清评论）：

System.out.println("It took " + year + " years to reach your goal");                                            
answer = scan.nextLine(); // This seems like a mistake

System.out.println("Would you like to try again? (y or n)");
dollars = scan.nextLine(); // This should be saved to answer, which the loop checks against

因此，在更正之后，while循环的结束应该如下所示：

System.out.println("It took " + year + " years to reach your goal");                                            

System.out.println("Would you like to try again? (y or n)");
answer = scan.nextLine();

Answer 2

它终止是因为在这一行之后：

 System.out.println("It took " + year + " years to reach your goal");                                            
 answer = scan.nextLine();

answer可能包含一个不是“y”的值并终止while循环。

在你要求再试一次后，你会这样做：

dollars = scan.nextLine();

在该行上将dollars更改为answer，然后删除answer = scan.nextLine();两行。

Answer 3

将scan.nextLine()更改为scan.next()

工作程序：

public static void main(String[] args)
{
    String answer = "y";
    double dollars;
    final double interest = 0.05;
    int year = 0;
    Scanner scan = new Scanner(System.in);

    while(answer.equals("y") )
    {
        System.out.println("How many dollars are deposited?");
        dollars = scan.nextDouble();


        while(dollars < 1000000.00)
        {
            dollars = dollars + dollars * interest;
            year = year + 1;
        }
           System.out.println("It took " + year + " years to reach your goal.");

           System.out.println("Would you like to try again? (y or n)");
           answer = scan.next();


    }

}

如何使这个哨兵控制循环工作？

3 个答案: