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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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481 Discussions

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  • 236sakshisingh
     + 0 comments

    public static final String regularExpression = "^[a-zA-Z][\w]{7,29}$";

  • devashis_k2002
     + 0 comments
        public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int size = scanner.nextInt();
        scanner.nextLine();
        for (int i = 0; i < size; i++) {
            System.out.println(scanner.nextLine().matches("[a-zA-Z][a-zA-Z0-9_]{7,29}") ? "Valid" : "Invalid");
        }
        scanner.close();
    }

  • vitalii_iandulov
     + 0 comments
    public static final String regularExpression = "[A-Za-z]\\w{7,29}";

  • kottemeghana250
     + 0 comments

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

  • sathish0723
     + 0 comments

    import java.io.; import java.util.;

    public class Solution {

    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 input = new Scanner(System.in);
   int count = input.nextInt();
    input.nextLine();

    for(int i=0;i<count;i++){
    String username = input.nextLine();


    if(checkUsername(username)){
        System.out.println("Valid");
    }
    else{
        System.out.println("Invalid");
    }
    }

    input.close();

}
public static boolean checkUsername(String username){
    int length = username.length();

    if(length<8 || length>30){
        return false;
    }
    if(!Character.isLetter(username.charAt(0))){
        return false;
    }

    for(int i=1;i<length;i++){
       char ch = username.charAt(i);
       if(!Character.isLetterOrDigit(ch) && ch!='_'){
        return false;
       }
    }
    return true;
}

    }