public ExtHashSet union(Collection c) {
ExtHashSet result = new ExtHashSet();
result.addAll(this);
result.addAll(c);
return result;
}
public ExtHashSet intersection(Collection c) {
ExtHashSet result = new ExtHashSet();
Object o;
Iterator i = c.iterator();
while (i.hasNext()) {
o = i.next();
if (this.contains(o)) {
result.add(o);
}
}
return result;
}