stream sorted进行降序排序升序降序

以你之姓@ 2022-11-07 00:54 383阅读 0赞

[https://blog.csdn.net/banjw\_129/article/details/83585135][https_blog.csdn.net_banjw_129_article_details_83585135]

List<StaffGenderVO> genderVOList = staffList.stream()
            .collect(Collectors.groupingBy(o -> NativePlaceUtil.getCityName(o.getIdNumber()), Collectors.counting()))
            .entrySet().stream().map(e -> new StaffGenderVO(e.getKey() , e.getValue().toString()))
            .collect(Collectors.toList()).stream()
            //降序
            .sorted((h1, h2) ->  convertToInteger(h2.getValue()).compareTo( convertToInteger(h1.getValue()) ))
            //前3个
            .limit(30)
            //终止流
            .collect(Collectors.toList());

根据value值的大小进行降序排序，并进行截取。

public static void main(String[] args) {
            List<Map<String, Object>> list = Lists.newArrayList();
            Map<String, Object> map = Maps.newHashMap();
            map.put("id", 1);
            map.put("value", 20);
            list.add(map);
            map = Maps.newHashMap();
            map.put("id", 2);
            map.put("value", 80);
            list.add(map);
            map = Maps.newHashMap();
            map.put("id", 3);
            map.put("value", 21);
            list.add(map);
            map = Maps.newHashMap();
            map.put("id", 4);
            map.put("value", 28);
            list.add(map);
            System.out.println("原始数据："+list);
            //根据value进行排序 得到升序排列
            list.sort(Comparator.comparing(h -> ConvertUtil.obj2Integer(h.get("value"))));
            //颠倒排序，变为降序排列
            Collections.reverse(list);
            //截取前3个
            System.out.println("结果"+list.subList(0, 3));
        }

使用1.8 stream处理

List<Map<String, Object>>result = list.stream().sorted((h1, h2) -> 
    //降序
    ConvertUtil.obj2Integer(h2.get("value")).compareTo(ConvertUtil .obj2Integer(h1.get("value"))))
    				//前3个
                    .limit(3)
                    //终止流
                    .collect(Collectors.toList());
      System.out.println("流结果"+result );

运行结果：

原始数据：[{id=1, value=20}, {id=2, value=80}, {id=3, value=21}, {id=4, value=28}]
    结果[{id=2, value=80}, {id=4, value=28}, {id=3, value=21}]

[https_blog.csdn.net_banjw_129_article_details_83585135]: https://blog.csdn.net/banjw_129/article/details/83585135