static boolean isValidCardLength(@Nullable String cardNumber) {
        return cardNumber != null && isValidCardLength(cardNumber,
                getPossibleCardType(cardNumber, false));
    }
static boolean isValidCardLength ( @ Nullable String cardNumber ) { return cardNumber != null && isValidCardLength ( cardNumber , getPossibleCardType ( cardNumber , false ) ) ; }
Checks to see whether the input number is of the correct length, after determining its brand.
This function does not perform a Luhn check.

@param cardNumber the card number with no spaces or dashes
@return {@code true} if the card number is of known type and the correct length