EDIT: As FearUs pointed out, a better solution is to use Guava’s Sets.powerset(Set set).
EDIT 2: Updated links.
Quick and dirty translation of this solution:
public static void main(String[] args) {
List<List<String>> powerSet = new LinkedList<List<String>>();
for (int i = 1; i <= args.length; i++)
powerSet.addAll(combination(Arrays.asList(args), i));
System.out.println(powerSet);
}
public static <T> List<List<T>> combination(List<T> values, int size) {
if (0 == size) {
return Collections.singletonList(Collections.<T> emptyList());
}
if (values.isEmpty()) {
return Collections.emptyList();
}
List<List<T>> combination = new LinkedList<List<T>>();
T actual = values.iterator().next();
List<T> subSet = new LinkedList<T>(values);
subSet.remove(actual);
List<List<T>> subSetCombination = combination(subSet, size - 1);
for (List<T> set : subSetCombination) {
List<T> newSet = new LinkedList<T>(set);
newSet.add(0, actual);
combination.add(newSet);
}
combination.addAll(combination(subSet, size));
return combination;
}
Test:
$ java PowerSet ted williams golden
[[ted], [williams], [golden], [ted, williams], [ted, golden], [williams, golden], [ted, williams, golden]]
$