public class Recursion {
    public static void main(String[] args) {
        Recursion recursion = new Recursion();
        List<Long> list = new ArrayList<Long>();
        Long num = null;

        recursion.recursionFunction_1(5L, list);
        recursion.recursionFunction_2(5L, num);
        System.out.println("recursionFunction_1:" + list.get(0));
        System.out.println("recursionFunction_2:" + num);
    }
    private void recursionFunction_1(Long i, List<Long> list) {
        i--;
        if (i == 0) {
            list.add(i);
        } else {
            recursionFunction_1(i, list);
        }
    }
    private void recursionFunction_2(Long i, Long num) {
        i--;
        if (i == 0) {
            num = i;
        } else {
            recursionFunction_2(i, num);
        }
    }
}