* @return iterator capable of iterating over {first, first+count} contacts
*/
public Iterator<Contact> iterator(int first, int count) {
SortParam sp = getSort();
if (queryParam == null) {
queryParam = new QueryParam(first, count, sp.getProperty(), sp
.isAscending());
} else {
queryParam.setFirst(first);
queryParam.setCount(count);
queryParam.setSort(sp.getProperty());