isUsername method
Validates if the given username
meets the required criteria.
The username must be between 3 and 16 characters long and include only letters, numbers, underscores, and dots.
Returns true
if the username
is valid, otherwise false
.
Implementation
bool isUsername(String username) {
bool usernameValid = RegExp(r'^[a-zA-Z0-9._]{3,16}$').hasMatch(username);
return usernameValid;
}