Question

我在使用这行代码时遇到了困难。代码是计算一个互联网服务账单，其中套餐A每月花费9.95美元，10小时，额外花费2.00美元。套餐B每月花费13.95美元，20小时，额外费用为1.00美元。套餐C每月花费19.95美元。我放入小时后，我不断收到此错误java.util.NoSuchElementException。

以下是代码：

import java.util.Scanner;

public class InternetServiceProvider {
    public static void main (String args[])
    {   
        while (true)
        {
            printMonthlyBill(calculateBill(getHours(), menu()));
        }
    }

    public static double getHours()
    {
        double hours;

        Scanner inputHours = new Scanner (System.in);

        System.out.print("Please enter the hours used: ");
        hours = inputHours.nextDouble();

        inputHours.close();

        return hours;
    }

    public static int menu ()
    {
        int packageChoice;

        Scanner userInput = new Scanner (System.in);

        System.out.println("Which package have you obtain? (Please use A, B, or C)");
        System.out.println("[1] Package A");
        System.out.println("[2] Package B");
        System.out.println("[3] Package C");
        System.out.print("Please select your package: ");
            packageChoice = userInput.nextInt();
        userInput.close();

        return packageChoice;
    }
}

这是输入：

    Please enter the hours used: 25
Which package have you obtain? (Please use A, B, or C)
[1] Package A
[2] Package B
[3] Package C
Please select your package: Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Unknown Source)
    at java.util.Scanner.next(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at InternetServiceProvider.menu(InternetServiceProvider.java:37)
    at InternetServiceProvider.main(InternetServiceProvider.java:8)

Answer 1

您正在关闭System.in。您应该在两种方法之间共享Scanner，并在完成后关闭。

public static void main (String args[])
{   
    try(Scanner input = new Scanner (System.in)) {
       while (true)
       {
           printMonthlyBill(calculateBill(getHours(input), menu(input)));
       }
    }
}

public static double getHours(Scanner input)
{
    double hours;



    System.out.print("Please enter the hours used: ");
    hours = input.nextDouble();

    return hours;
}

public static int menu (Scanner input)
{
    int packageChoice;

    System.out.println("Which package have you obtain? (Please use A, B, or C)");
    System.out.println("[1] Package A");
    System.out.println("[2] Package B");
    System.out.println("[3] Package C");
    System.out.print("Please select your package: ");
        packageChoice = input.nextInt();

    return packageChoice;
}

java util没有这样的元素异常问题

1 个答案: