customException5.java

public class Main {

    public static void main(String[] args) throws Exception {

        PreCheck preCheck = new PreCheck("4543 5807 9574 0027");
        preCheck.validation();
    }
    private static class PreCheck {
        private String _cardNumber;
        
        public PreCheck(String cardNumber){
            _cardNumber = cardNumber;
        }
        public void validation() throws ValidationException {
            if (_cardNumber.contains("4543")) {
                System.out.println("Login Successful..");
            } else {
                throw new ValidationException("Login Failed..");
            }
        }
    }
}