recursiv subset (different length, same order)

subset.java

private static void recSubsets(String soFar, String rest) {
    if (rest.equals("")) {
        System.out.println(soFar);
    } else {
        recSubsets(soFar + rest.charAt(0), rest.substring(1));
        recSubsets(soFar, rest.substring(1));
    }
}