switch留个爪，之后还需要再研究下

 public class SwitchDemo
 {
     public static void main (String [] args)
     {
         for(int i = 0; i < 10; i++)
         {
             char c = (char) (Math.random() * 26 + 'a');
             System.out.print (c + ": ");
             switch (c)
             {
                 case 'a':
                 case 'e':
                 case 'i':
                 case 'o':
                 case 'u':
                         System.out.println("vowel");
                         break;
                 case 'y':
                 case 'w':
                         System.out.println("Sometimes a vowel");
                         break;
                 default:
                         System.out.println("consonant");}
         }
     }
 }