import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;/*** User: ldj* Date: 2023/3/22* Time: 23:58* Description: 数据分页展示逻辑*/
public class SublistDemo {public static void main(String[] args) {List list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12);System.out.println(list.subList(0, 5)); //从下表0开始右取5-0个元素System.out.println(queryPage(1, 5, list));System.out.println(queryPage(3, 5, list));System.out.println(queryPage(4, 5, list));int pageNo = 4, pageSize = 5;queryPage2(list, pageNo, pageSize);}public static List queryPage(int pageNum, int pageSize, List list) {if (pageNum < 0 || pageSize < 0) {throw new RuntimeException("参数不能是负数");}if (list.size() % pageSize == 0) {int maxPageNum = list.size() / pageSize;if (pageNum <= maxPageNum && pageNum > 0) {int fromIndex = (pageNum * pageSize) - pageSize;int toIndex = pageNum * pageSize;return list.subList(fromIndex, toIndex);}}if (list.size() % pageSize > 0) {int maxPageNum = list.size() / pageSize + 1;if (pageNum > 0) {if (pageNum <= maxPageNum - 1) {//也可以变形一下,//int fromIndex = (pageNum * pageSize) - pageSize == (pageNum-1) * pageSize;//int toIndex = pageNum * pageSize == fromIndex + pageSize;int fromIndex = (pageNum - 1) * pageSize;int toIndex = fromIndex + pageSize;return list.subList(fromIndex, toIndex);}//最后一页不满pageSizeif (pageNum == maxPageNum) {int fromIndex = (pageNum * pageSize) - pageSize;int toIndex = list.size();return list.subList(fromIndex, toIndex);}}}return null;}//Stream APIprivate static void queryPage2(List list, int pageNo, int pageSize) {List subList = list.stream().skip((long) (pageNo - 1) * pageSize).limit(pageSize).collect(Collectors.toList());System.out.println(subList);}}