Program Java tentang Switch

Tentang Switch:

import java.util.*;
public class Switch {

public static void main (String[] args) {
Scanner in = new Scanner (System.in);
char key;
String s1;

do
{
System.out.println("input Huruf a-d");
s1 = in.nextLine();
key = s1.charAt(0);

switch (key){
case 'a':
System.out.println("Anda Memilih huruf a");
break;
case 'b':
System.out.println("Anda Memilih huruf b");
break;
case 'c':
System.out.println("Anda Memilih huruf c");
break;
case 'd':
System.out.println("Anda Memilih huruf d");
break;
case 'x':
System.out.println("Exit!!!!!");
break;
default:
System.out.println ("Huruf yang anda masukkan salah");
break;
}
} while (key != 'x');
}

}