使用if语句验证switch语句

• 使用switch语句实现菜单。允许用户输入正确的大写/小写字母（即AIR或air或Air或aiR等）。如果用户输入了无效的选择，则您的程序应告诉他们，然后退出。
• 空气，水和钢的答案必须使用printf。将空气显示为3个小数位，将水显示为4个小数位，将钢显示为5个小数位。
• 在用户输入距离之后，声波必须传播，但是在计算中使用该数字之前，请对其进行验证。如果距离小于零或大于10000，则显示错误消息，并且不做进一步处理，即退出。将switch语句（菜单–参见上文）嵌套在此if语句中。

import java.util.Scanner;

   public class SpeedSound
   {
     public static void main(String[] args)
     {
        String input;       
        double distance;
        double time;
        final double AIR   = 1/1100;
        final double WATER = 1/4900;
        final double STEEL = 1/16400;

        Scanner kyb = new Scanner(System.in);

        System.out.print("Enter the corresponding medium:\n ");
        System.out.println("Air\n ");
        System.out.println("Water\n ");
        System.out.println("Steel\n ");
        input = kyb.nextLine();

        System.out.print("Enter the distance: ");   
        distance = kyb.nextDouble();

       if (distance < 0 || distance > 10000)
             System.out.print("Error: ");

           switch (input)
            {
                case "Air":
                case "AIR":
                time = (distance / 1100);
           System.out.println("The total time traveled is " + time + "seconds.");
        break;

        case "Water":
        case "WATER":   
        time = (distance / 4900);
        System.out.println("The total time traveled is " + time + "seconds.");
        break;

        case "Steel":
        case "STEEL":
        time = (distance / 16400);
        System.out.println("The total time traveled is " + time + "seconds.");
        break;

        }
     }
   }