get the powerset of a set

Powersets.java

import java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class Powerset {
    static Set<Set<Integer>> powerSet(Set<Integer> s) {
        Set<Set<Integer>> ps = new HashSet<Set<Integer>>();
        powerSet(s, new HashSet<Integer>(), ps);
        return ps;
    }
    
    static void powerSet(Set<Integer> s, Set<Integer> accum, Set<Set<Integer>> ps) {
        if (s.isEmpty()) {
            ps.add(new HashSet<Integer>(accum));
        } else {
            Iterator<Integer> it = s.iterator();
            int i = it.next();
            it.remove();
            accum.add(i);
            powerSet(new HashSet<Integer>(s), new HashSet<Integer>(accum), ps);
            accum.remove(i);
            powerSet(new HashSet<Integer>(s), new HashSet<Integer>(accum), ps);
        }
    }
    
    public static void main(String[] args) {
        System.out.println(powerSet(new HashSet<Integer>(Arrays.asList(1,2,3))));
    }
}