java - 在第一个循环后执行 while 循环不正确打印

Question

我正在尝试执行一个 do-while 循环，使程序在用户输入“y”或“Y”后再次迭代，但每次我运行该程序时，它都会打印出如下内容:

Would you like to try again?Enter Y for yes or N for no:  [DrJava Input Box] (I enter y)Are you a student? (no input box is shown, and it skips it)Are you a member of staff or faculty? [DrJava Input Box] (i enter yes or no)How many tickets do you need? [DrJava Input Box] (I enter an int, but it doesnt complete that part where it shows how many tickets sold or how much it costs)Would you like to try again? Enter Y for yes or N for no: [DrJava Input Box]

this is what my program looks like:

import java.util.Scanner;

public class Ticket
{
    public static void main(String[] args)
    {
        Scanner keyboard = new Scanner(System.in);

        double ticketprice = 12.00;
        double result;
        double result2;
        double result3;
        char repeat;
        String input;
        String student;
        String staff;
        int ticket;

        do
        {
            System.out.println("Are you a student?");
            student = keyboard.nextLine();


            System.out.println("Are you a member of staff or faculty?");
            staff = keyboard.nextLine();


            System.out.println("How many tickets do you need?");
            ticket = keyboard.nextInt();



            if(student.equals("yes"))
            {
                System.out.println("Here is your " + ticket + " tickets for $0.00");
                }


            if(staff.equals("yes"))
            {
                result = ticketprice * .85;
                result2 = ticket * result;
                System.out.printf("Here are your " + ticket + " tickets for $%.2f\n", result2);
                }



            if(student.equals("no") && staff.equals("no"))
            {
                result3 = ticket * ticketprice;
                System.out.printf("Here are your " + ticket + " tickets, for $%.2f\n", result3);
                }


            System.out.println("Would you like to try again?");
            System.out.print("Enter Y for yes or N for no: ");
                input = keyboard.next();
            repeat = input.charAt(0);

        }
        while(repeat == 'y' || repeat == 'Y');

    }
}

我是编程初学者，所以任何帮助都会很好。谢谢。

Answer 1

在循环结束时，您调用 next() 来读取“重试”响应。这会读取下一个标记，但仍会留下以输入流结尾的行。

下一次通过循环，当您调用 nextLine() 来读取“您是学生吗”响应时，它会立即读取该行的剩余部分。

最简单的解决方案是:

• 使用 nextLine() 而不是 next() 来提示“再试一次”，但这意味着您必须处理左边结尾的行通过 nextInt() 在“门票”问题中，那么您还必须...
• 使用 nextLine() 而不是 nextInt() 来解决“门票”问题，然后使用 Integer.parseInt() 解析字符串转换成一个整数。

由于您的所有响应似乎都只是单个单词响应，因此另一种选择是在任何地方都使用 next()/nextInt() 而不是使用 nextLine() 完全没有。关键是，当您将两者混合使用时，您必须了解它们如何相互作用。