Java Luhn算法卡号生成器

Luhn算法是一种用于验证卡号、信用卡号等一些标识号码有效性的算法。以下是一个基于Java语言实现的Luhn算法卡号生成器：

import java.util.Random;

public class LuhnCardGenerator {
    private static final int CARD_NUMBER_LENGTH = 16;

    public static void main(String[] args) {
        String cardNumber = generateCardNumber();
        System.out.println("Generated card number: " + cardNumber);
    }

    private static String generateCardNumber() {
        Random random = new Random();
        StringBuilder sb = new StringBuilder();

        // Generate first 15 digits randomly
        for (int i = 0; i < CARD_NUMBER_LENGTH - 1; i++) {
            sb.append(random.nextInt(10));
        }

        // Calculate the Luhn check digit
        int checkDigit = calculateCheckDigit(sb.toString());
        sb.append(checkDigit);

        return sb.toString();
    }

    private static int calculateCheckDigit(String cardNumber) {
        int sum = 0;
        boolean isSecondDigit = false;

        for (int i = cardNumber.length() - 1; i >= 0; i--) {
            int digit = Integer.parseInt(cardNumber.substring(i, i + 1));

            if (isSecondDigit) {
                digit *= 2;
                if (digit > 9) {
                    digit = digit % 10 + 1;
                }
            }

            sum += digit;
            isSecondDigit = !isSecondDigit;
        }

        return (10 - sum % 10) % 10;
    }
}

该算法生成一个16位的随机卡号，并且最后一位是Luhn算法的校验位。可以通过调用`generateCardNumber()`方法来获得生成的卡号。