Order submitted, Trades... require paging process

[Min2dat]

CoinTossX/Web/src/main/java/wicket/dataProvider

public class OrderDataProvider extends SortableDataProvider<OrderVO, String>
@OverRide
public Iterator<? extends OrderVO> iterator(long first, long count) {
List newList = new ArrayList(orders);
return newList.subList((int)first, (int)(first + count)).iterator();
//return orders.iterator();
}

I did it by forcibly casting the long type to int, but I am worried about the memory when the data grows.