java - while语句循环错误

Question

嘿，我对这段代码一直有疑问，因为当我输入字符串重复值时它没有循环。我无法理解我做错了什么。

import java.util.Scanner;
public class MpgCalculator
{
    public static void main(String[]args)
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("Welcome to the MPG and CPM Calculator!");
        double startOd, endOd, gallons, cost, mpg, cpm;
        String repeat = "yes";
        while(repeat.equals("yes")||repeat.equals("Yes")||repeat.equals("y")||repeat.equals("Y"))
        {
            System.out.println("Please Enter:");
            System.out.print("\tYour Starting Odometer Reading: ");
            startOd = sc.nextDouble();
            System.out.print("\tYour Ending Odometer Reading: ");
            endOd = sc.nextDouble();
            System.out.print("\tThe Amount of Gallons Used: ");
            gallons = sc.nextDouble();
            System.out.print("\tThe Cost-per-Gallon That You Spent: ");
            cost = sc.nextDouble();
            mpg = getMpg(startOd, endOd, gallons);
            cpm = getCpm(mpg, cost);
            System.out.println("\nYour Miles-per-Gallon is " + mpg + ".");
            System.out.println("Your Cost-per-Mile is " + cpm + ".");
            System.out.print("Do it again? ");
            repeat = sc.nextLine();
        }
    }
    public static double getMpg(double startOd, double endOd, double gallons)
    {
        double mpg;
        mpg = (endOd - startOd) / gallons;
        return mpg;
    }
    public static double getCpm(double mpg, double cost)
    {
        double cpm;
        cpm = cost / mpg;
        return cpm;
    }
}

Answer 1

如果不需要额外的行，请将 repeat = sc.nextLine(); 更改为 repeat = sc.next();。只有当您是下一行时它才会获取它，而您不是，因此它会终止程序。