ValidUsername

package P07_ValidUsernames;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String pattern = "^[A-Za-z\\_\\-0-9]{3,16}$";
        //String pattern = "^[\\w-]{3,16}$";

        String line = scanner.nextLine();
        while(!"END".equals(line)){

            Pattern regex = Pattern.compile(pattern);
            Matcher matcher = regex.matcher(line);

            if(matcher.find()){
                System.out.println("valid");
            }else{
                System.out.println("invalid");
            }

            line = scanner.nextLine();
        }
    }
}