Input Format

The first line of input contains an integer , describing the total number of usernames. Each of the next  lines contains a string describing the username. The locked stub code reads the inputs and validates the username.

Constraints

  • The username consists of any printable characters.

Output Format

For each of the usernames, the locked stub code prints Valid if the username is valid; otherwise Invalid each on a new line.


hackerrank valid username regular expression solution in java


Valid username Regular expression problem solution in java | HackerRank


import java.util.Scanner;
class UsernameValidator {
    /*
     * Write regular expression here.
     */
     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");
            }           
        }
    }
}