This function generates and returns all subsets of a list using iteration

subsets_iterative.java

    private static List<List<Integer>> subsetIterative(List<Integer> elements) {
        System.out.println("Subsets of " + elements);

        List<List<Integer>> subsets = new ArrayList<>();
        List<Integer> subset;
        String subsetBinary;

        int numberOfElements = elements.size();
        for (int i = 0; i < (1 << numberOfElements); i++) {
            subsetBinary = convertToZeroPaddedBinaryString(i, numberOfElements);

            subset = new ArrayList<>();
            for (int j = 0; j < numberOfElements; j++) {
                if (subsetBinary.charAt(j) == '1') {
                    subset.add(elements.get(j));
                }
            }
            subsets.add(subset);
            System.out.println(String.format("%s: %s", subsetBinary, subset));
        }
        return subsets;
    }

    private static String convertToZeroPaddedBinaryString(int number, int padWidth) {
        return String.format("%" + padWidth + "s", Integer.toBinaryString(number)).replaceAll(" ", "0");
    }