Java家庭作业用户输入问题

Question

我有一个班级任务要使用扫描仪读取数据。

import java.util.Scanner;

public class Project23
{
    public static void main(String[] args)
    {
        // Declarations and instantiations.
        Scanner scan = new Scanner(System.in);
        String any = "";
        boolean more = false;
        double purchase = 0.0;

        // Ask if user would like to run program?
        System.out.print("Do you have any purchases? Y/N?: ");

        // Ready value into string.
        any = scan.nextLine();
        System.out.println();

        // If any is equal to y or Y it will set the value of more to true
        // this runs the while statement below.
        more = any.toUpperCase().equals("Y");

        // While more is still true continue to run the code within the brackets.
        while (more)
        {
            System.out.print("Please input purchase amount: ");
            purchase += scan.nextDouble();
            System.out.println();

            System.out.print("Do you have any more purchases Y/N?: ");
            any = scan.nextLine();
            System.out.println();

            more = any.toUpperCase().equals("Y");
        }

        if (purchase >= 2500)
            System.out.println("Purchase >= 2500");
        else
            System.out.println("Purchase < 2500");
    }
}

最下面的部分是对我的测试，以检查是否一切正常。但是，虽然我已设置了while循环，但似乎不想继续运行一次以上。它会取一个值，然后如果我说是，我有更多的值（y或Y），它将退出并打印两个笨蛋

Answer 1

scan.nextLine（）时，它将读取不等于Y或y的结束符。结果，它退出了while循环。像这样更正您的代码，只需更改您正在阅读doubel的一行即可：

while(more){

    System.out.print("Please input purchase amount: ");
    purchase+=Double.parseDouble(scan.nextLine());
    System.out.println();
    System.out.print("Do you have any more purchases Y/N?: ");
    // scan.nextLine();
    String any1=scan.nextLine();
    System.out.println();       
    more = any1.equals("y") || any1.equals("Y");//Shortened :)
}