HackerRank Java- Valid Username Regular Expression

You are updating the username policy on your company's internal networking platform. According to the policy, a username is considered valid if all the following constraints are satisfied:

import java.util.Scanner;
class UsernameValidator {
    public static final String regularExpression = "^[a-zA-Z][\\w]{7,29}$";
    //public static final String regularExpression = null;
}


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");
            }           
        }
    }
}