@Override
 public PreferenceArray getPreferencesForItem(long itemID) throws NoSuchItemException {
   FastIDSet userIDs = preferenceForItems.get(itemID);
   if (userIDs == null) {
     throw new NoSuchItemException(itemID);
   }
   PreferenceArray prefArray = new BooleanItemPreferenceArray(userIDs.size());
   int i = 0;
   LongPrimitiveIterator it = userIDs.iterator();
   while (it.hasNext()) {
     prefArray.setUserID(i, it.nextLong());
     prefArray.setItemID(i, itemID);
     i++;
   }
   return prefArray;
 }