import java.util.Arrays;
import java.util.Collections;
import java.util.List;

/**
 * Created by Hung on 4/27/17.
 */
public class ListOperator {

    public static class Order {}

    public static <T> List<T> getPage(List<T> sourceList, int page, int pageSize) {
        if(pageSize <= 0 || page <= 0) {
            throw new IllegalArgumentException("invalid page size: " + pageSize);
        }

        int fromIndex = (page - 1) * pageSize;
        if(sourceList == null || sourceList.size() < fromIndex){
            return Collections.emptyList();
        }

        // toIndex exclusive
        return sourceList.subList(fromIndex, Math.min(fromIndex + pageSize, sourceList.size()));
    }


    public static void main(String[] args) {

        List<Order> orders = Arrays.asList(new Order(), new Order(), new Order(), new Order(), new Order(), new Order());

        int totalPage = orders.size()/2;

        System.out.println(totalPage);

        System.out.println(getPage(orders, 1, 2));
        System.out.println(getPage(orders, 2, 2));
        System.out.println(getPage(orders, 10, 2));
        System.out.println(getPage(orders, 5, 2));
        System.out.println(getPage(orders, 6, 2));


    }
}