stream 有什么办法对分组后的每组元素内部进行排序吗

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Map<String, List<introductionvideopagedto>> map = videoPageDtoList.stream().collect(Collectors.groupingBy(dto -> dto.getDataId()));</introductionvideopagedto>

"3": [ { "id": "96ab01d10d66bb0fe41d3fc65b7eeca4", "title": "视频标题", "videoUrl": "11111111111", "dataId": "3", "sort": 2, "createTime": 1564041929000 }, { "id": "ef510c786580637e831ea532e925a312", "title": "课程标题课程标题", "videoUrl": "222222222222", "dataId": "3", "sort": 3, "createTime": 1568791200000 }, { "id": "efa01867ea0d6cf4cccc0020203c6928", "title": "课程标题", "videoUrl": "333333333333333333333333333333333333333", "dataId": "3", "sort": 1, "createTime": 1568790906000 } ]

groupingBy 之后的这个 map 中 key stream 好像是默认已经排序了? 接着还想在组内对 sort 进行排序

2 replies • 2019-09-23 19:39:26 +08:00

ayonel

Sep 23, 2019

必须一步到位么？
https://stackoverflow.com/questions/29610465/sort-the-values-in-a-map-of-type-mapstring-liststring 这个两步可解决
第二步：map.values().stream().forEach(l->l.sort(Compartor)) 大概这样

Tsukihime

Sep 23, 2019

list.stream()
.sorted(Comparator.comparing(IntroductionVideoPageDTO::getSort))
.collect(Collectors.groupingBy(IntroductionVideoPageDTO::getDataId));