/* ---- ArrayList and HashSet approach (order maintained) ---- */
  public static void test_HashSet_listOrder(ArrayList a_master)
  {
    ArrayList a = new ArrayList(a_master);
    long cur = System.currentTimeMillis();
    Set set = new HashSet();
    List newList = new ArrayList();
    for (Iterator iter = a.iterator(); iter.hasNext(); ) {
      Object element = iter.next();
      if (set.add(element))
        newList.add(element);
    }
    a.clear();
    a.addAll(newList);
    long diff = System.currentTimeMillis()-cur;
    System.out.println(
      "ArrayList/HashSet approach (list order) = "+diff+" ms");
  }