https://www.hackerrank.com/challenges/valid-username-checker/problem?isFullScreen=true
//글자수 8~30
//영어로 시작, 숫자로 시작하면 안됨
//특수문자 안됨.
1차)
input값 중에 Samantha_21 가 Valid로 나와야 함.
조건 하나 놓쳤었음. 특수문자는 _ (언더바만 허용)
import java.util.Scanner;
class UsernameValidator {
/*
* Write regular expression here.
*/
// public static final String regularExpression = null;
// public static final String regularExpression = "^[A-Za-z]([A-Za-z0-9]{7,29})$";
public static final String regularExpression = "^[A-Za-z]([A-Za-z0-9\\_]{7,29})$";
}
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");
}
}
}
}
You are updating the username policy on your company's internal networking platform. According to the policy, a username is considered valid if all the following constraints are satisfied:
- The username consists of to characters inclusive. If the username consists of less than or greater than characters, then it is an invalid username.
- The username can only contain alphanumeric characters and underscores (_). Alphanumeric characters describe the character set consisting of lowercase characters , uppercase characters , and digits .
- The first character of the username must be an alphabetic character, i.e., either lowercase character or uppercase character .
For example:
UsernameValidityINVALID; Username length < 8 characters | |
VALID | |
VALID | |
INVALID; Username begins with non-alphabetic character | |
INVALID; '?' character not allowed |
Update the value of regularExpression field in the UsernameValidator class so that the regular expression only matches with valid usernames.
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.
Sample Input 0
8
Julia
Samantha
Samantha_21
1Samantha
Samantha?10_2A
JuliaZ007
Julia@007
_Julia007
Sample Output 0
Invalid
Valid
Valid
Invalid
Invalid
Valid
Invalid
Invalid
Explanation 0
Refer diagram in the challenge statement.
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