"[^\d][a-zA-Z0-9_]{8,30}" - why this answer is wrong. double slashes next to d In IntelliJ the above regex works.

Your "Valid Username Regular Expression" is incredibly helpful! It's like finding the perfect retirement plan for retiring in Thailand. This regex makes username validation a breeze, just like planning your dream retirement destination. Thanks for sharing this valuable tool!

JAVA__7

class UsernameValidator {
    public static final String regularExpression = "[A-Za-z][A-Za-z0-9_]{7,29}";
}

 public static void main(String[] args) {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
Scanner in = new Scanner(System.in);
Pattern search = Pattern.compile("[\\W]");

int count=0;


  int total = in.nextInt();

  while(count<total){

    String s= in.next();
    Matcher match = search.matcher(s);

     if(s.length()<8 || s.length()>30 )
      System.out.println("Invalid");



if(s.length()>=8 && s.length()<=30) 
    if((Character.isUpperCase(s.charAt(0))||Character.isLowerCase(s.charAt(0))) && !match.find())
      System.out.println("Valid"); 
      else System.out.println("Invalid");

    count++;

    }



}

}