JAVA错误: Utilizing Switch Statements

Question

这个问题已经有答案了:

Varying behavior for possible loss of precision (1 个回答)

已关闭 9 年前。

我是编程新手，有一些错误。当我用 Java 构建代码时出现此错误，它与 int 和 double 有关。这是我的代码:

import java.util.Scanner;
import java.text.DecimalFormat;

public class Overloader 
{
    public static void main(String[] args) 
    {
        Scanner k1 = new Scanner(System.in);
        double selection = 0, radius, height;

        do 
        {
            System.out.println("Select the options from [1-3]");
            System.out.println("1- Volume of the Cylinder");
            System.out.println("2- Volume of the Sphere");
            System.out.println("3- Exit");
            selection = k1.nextDouble();

            switch (selection) 
            {
                case 1:
                    System.out.print("Enter radius: ");
                    radius = k1.nextDouble();
                    System.out.print("Enter height: ");
                    height = k1.nextDouble();
                    System.out.printf("Volume = %10.3f%n", getVolume(radius, height));
                    break;
                case 2:
                    System.out.print("Enter radius: ");
                    radius = k1.nextDouble();
                    System.out.printf("Volume = %10.3f%n", getVolume(radius));
                break;
                case 3:
                    System.exit(0);
                default:
                    System.out.println("Incorr... choice!");
            } // end switch
        } while (selection != 3);
    }

    public static double getVolume(double radius, double height) 
    {
        return Math.PI * radius * radius * height;
    }

    public static double getVolume(double radius) 
    {
        return (4.0 / 3.0) * Math.PI * Math.pow(radius, 3);
    }
}

调试器说:

switch (selection) {
        ^
  required: int
  found:    double
1 error
Process completed.

请帮忙，我将不胜感激。非常感谢。

Answer 1

开关不能基于 double 型或浮点型。根据数据范围，你可能需要替换

selection = k1.nextDouble();

与

selection = k1.nextInt;

(并且选择被声明为 int，由 Ingo 指定)