Java 为什么赢了'；t代码转到下一行，提示用户退出或继续

我有一个程序，可以计算用户选择形状的面积。我提供了4种形状，在它们消失后，我想提示它们继续或退出。但是，在程序请求shape和all之后，它会停止，并且在第一个switch语句之后不会进入任何代码

我尝试将代码作为switch语句的一部分，但由于错误，它无法运行。我还试着做了另一个开关，你可以看到，但什么也没有

import java.util.Scanner;
import java.lang.Math;
public class area
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
String square;
String circle;
String rectangle;
String triangle;

System.out.println("Please choose one of the shapes you want the area of.");
System.out.println("Square, Circle, Rectangle, Triangle.");
String shape = scan.nextLine();
    switch (shape)
    {
        case "Square":
        System.out.println("Please enter the length of one side of the square.");
        double squareLength = scan.nextDouble();
        double squareArea = (squareLength * squareLength);
        System.out.println("The area of your square is "+ squareArea + ".");
        break;
        case "Circle":
        System.out.println("Please enter the radius of the circle.");
        double circleRadius = scan.nextDouble();
        double circleArea = (circleRadius * circleRadius)*Math.PI;
        System.out.println("The area of your circle is " + circleArea + ".");
        break;
        case "Rectangle":
        System.out.println("Please enter the width of the rectangle.");
        double rectangleWidth = scan.nextDouble();
        System.out.println("Please enter the length of the rectangle.");
        double rectangleLength = scan.nextDouble();
        double rectangleArea = (rectangleWidth * rectangleLength);
        System.out.println("The area of your rectangle is " + rectangleArea + ".");
        break;
        case "Triangle":
        System.out.println("Please enter the height of the trangle.");
        double triangleHeight = scan.nextDouble();
        System.out.println("Please enter the base of the trangle.");
        double triangleBase = scan.nextDouble();
        double triangleArea = (triangleHeight * triangleBase) / 2;
        System.out.println("The area of your triangle is " + triangleArea + ".");
        break;
        default:
        System.out.println("Please choose an option.");
    }
    System.out.println("Press c to continue and or q to quit.");
    String option = scan.nextLine();
    switch (option)
    {
        case "c":
        break;
        case "q":
        System.out.println("Have a good day!");
        break;
    }

    }
    }

---

程序只运行到第一个switch语句，之后的一切都不会发生。

首先，您需要将

开关盒

放入

while循环

，这样，当

选项

等于“c”时，程序将执行。 第二，上面的家伙在使用next（）或nextFoo（）后，放置了一个参考

扫描仪的可能副本跳过nextLine（）？

。因此，当您使用

nextDouble

读取一个值，然后尝试使用

nextLine

读取时，scan将跳过下一个

nextLine

。在此之后，您需要放置另一个

nextLine

，以便程序识别它

public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String option = "c";

        while(option.equals("c")){    
            System.out.println("Please choose one of the shapes you want the area of.");
            System.out.println("Square, Circle, Rectangle, Triangle.");
            String shape = scan.nextLine();
            switch (shape) {
                case "Square":
                    System.out.println("Please enter the length of one side of the square.");
                    double squareLength = scan.nextDouble();
                    double squareArea = (squareLength * squareLength);
                    System.out.println("The area of your square is " + squareArea
                            + ".");
                    break;
                case "Circle":
                    System.out.println("Please enter the radius of the circle.");
                    double circleRadius = scan.nextDouble();
                    double circleArea = (circleRadius * circleRadius) * Math.PI;
                    System.out.println("The area of your circle is " + circleArea
                            + ".");
                    break;
                case "Rectangle":
                    System.out.println("Please enter the width of the rectangle.");
                    double rectangleWidth = scan.nextDouble();
                    System.out.println("Please enter the length of the rectangle.");
                    double rectangleLength = scan.nextDouble();
                    double rectangleArea = (rectangleWidth * rectangleLength);
                    System.out.println("The area of your rectangle is "
                            + rectangleArea + ".");
                    break;
                case "Triangle":
                    System.out.println("Please enter the height of the trangle.");
                    double triangleHeight = scan.nextDouble();
                    System.out.println("Please enter the base of the trangle.");
                    double triangleBase = scan.nextDouble();
                    double triangleArea = (triangleHeight * triangleBase) / 2;
                    System.out.println("The area of your triangle is " + triangleArea
                            + ".");
                    break;
                default:
                    System.out.println("Please choose an option.");
                    break;

            }
            scan.nextLine();
            System.out.println("Press c to continue and or q to quit.");
            option = scan.nextLine();
        }
}