Subset

public class Subset {
    public static void main(String[] args) {

        Subset sub = new Subset();
        int[] arr = new int[] { 1, 2, 3 };
        sub.subsets(arr);
    }

    List<List<Integer>> opList = new ArrayList<>();

    public List<List<Integer>> subsets(int[] nums) {
        int temp[] = new int[nums.length];
        printAll(nums, nums.length, 0, temp, 0);
        return opList;
    }

    public void printAll(int[] arr, int n, int i, int[] temp, int s) {

        if (i == n) {
            List<Integer> minList = new ArrayList<>();
            for (int j = 0; j < s; j++) {
                minList.add(temp[j]);
            }
            opList.add(minList);
            return;
        }
        temp[s] = arr[i];

        printAll(arr, n, i + 1, temp, s + 1); // yes
        printAll(arr, n, i + 1, temp, s);// no

    }
}