Valid Username Regular Expression

  • + 0 comments
    import java.util.Scanner;
    class UsernameValidator {
        public static final String regularExpression = "^[a-zA-Z][a-zA-Z0-9_]{7,29}$";
    }
    
    
    public class Solution {
        private static final Scanner scan = new Scanner(System.in);
        
        public static void main(String[] args) {
            int n = Integer.parseInt(scan.nextLine());
            while (n-- != 0) {
                String userName = scan.nextLine();
    
                if (userName.matches(UsernameValidator.regularExpression)) {
                    System.out.println("Valid");
                } else {
                    System.out.println("Invalid");
                }           
            }
        }
    }