Check Credit Card Validity using Luhn Algorithm

Question

I tried to check the validation of credit card using Luhn algorithm, which works as the following steps:

1. Double every second digit from right to left. If do

Answer 1

There are two ways to split up your int into List

1. Use %10 as you are using and store it into a List
2. Convert to a String and then take the numeric values

Here are a couple of quick examples

public static void main(String[] args) throws Exception {
    final int num = 12345;
    final List nums1 = splitInt(num);
    final List nums2 = splitString(num);
    System.out.println(nums1);
    System.out.println(nums2);
}

private static List splitInt(int num) {
    final List ints = new ArrayList<>();
    while (num > 0) {
        ints.add(0, num % 10);
        num /= 10;
    }
    return ints;
}

private static List splitString(int num) {
    final List ints = new ArrayList<>();
    for (final char c : Integer.toString(num).toCharArray()) {
        ints.add(Character.getNumericValue(c));
    }
    return ints;
}