PowerSet Calculation in java

gistfile1.txt

import java.util.HashSet;
import java.util.Set;


public class PowerSet {

  private Set<Set<Object>> powerSet;
	
	
	private void setCombinations(Set<Object> set) {
		
		powerSet.add(set);
		if (set != null && !set.isEmpty()) {
			for (Object obj : set) {
				Set<Object> setWithoutObj = new HashSet<Object>();
				setWithoutObj.addAll(set);
				setWithoutObj.remove(obj);
				
				if (powerSet.contains(setWithoutObj)) {
					continue;
				} else {
					setCombinations(setWithoutObj);
				}
				System.out.println("leftSet " + set);
			}
		}
	}
	
	public String toString() {
		return powerSet.toString();
	}
	
	public PowerSet(Set<Object> objects) {
		powerSet = new HashSet<Set<Object>>();
		
		// Calculate combinations with the original and the empty set
		setCombinations(objects);
	}
	
	public static void main(String[] args) {
		Set s = new HashSet();
		s.add("a");
		s.add("b");
		s.add("c");
		
		PowerSet p = new PowerSet(s);
		
		System.out.println(p);
	}
	
}