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  1. Prepare
  2. Java
  3. Strings
  4. Valid Username Regular Expression
  5. Discussions

Valid Username Regular Expression

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471 Discussions

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  • jhoneder
     + 0 comments

    import java.util.Scanner;

    public class Solution {

    public static void main(String[] args) {

    String REGEX_USER_NAME = "^[a-zA-Z]\\w{7,29}$";
    Scanner in = new Scanner(System.in);
    int numTests = Integer.parseInt(in.nextLine());

    while (numTests-- > 0) {
        String username = in.nextLine();
        System.out.println(username.matches(REGEX_USER_NAME) ? "Valid" : "Invalid");
    }
    in.close();
}

    }

  • sujaldaware7721
     + 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");
        }           
    }
}

    }

  • jaidisrujanredd1
     + 0 comments

    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.length()>=8 && userName.length()<=30){
            char firstChar=userName.charAt(0);
            if(userName.matches("[a-zA-Z0-9_]*") && Character.isLetter(firstChar)){
                System.out.println("Valid");
            }else{
                System.out.println("Invalid");
            }
        }else{
            System.out.println("Invalid");
        }
}

    }}

  • kushkapoor6707
     + 0 comments

    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");
    }           
}

    } }

  • souravpaitandy
     + 1 comment

    Just update the 'regularExpression' with the following expression:

    public static final String regularExpression ="[a-zA-Z][a-zA-Z0-9_]{7,29}";

    `