Hi how can i use a sentinel controlled loop to keep prompting the user to enter the next character after it computes whether the char is a digit or a vowel till the user inputs a sentinel character '#' it will exit the program.

import java.util.Scanner;
class test1 {

public static void main(String[] args) {
Scanner zz= new Scanner(System.in);
System.out.println("Enter a character:");
String s = zz.next();
char input = s.charAt(0);


if (input=='a'||input=='e'||input=='i'||input=='o'||input=='u') {
System.out.println("Vowel");
}
else if(Character.isDigit(input))
{
System.out.println("Digit");
}

}
}