java8 stream() 去重分组

最新推荐文章于 2025-06-21 15:59:00 发布

ml863606

最新推荐文章于 2025-06-21 15:59:00 发布

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本文链接：https://blog.youkuaiyun.com/ml863606/article/details/106214407

本文详细介绍了使用Java Stream API进行集合操作的高级技巧，包括去重、分组等，通过具体示例展示了如何利用TreeSet和Comparator实现高效的数据处理。

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   //去重
            ArrayList<JiTuanAddressModel> schoolListFinal1 = jiTuanAddressModelsNew.stream().collect(
                    collectingAndThen(
                            toCollection(() -> new TreeSet<>(Comparator.comparing(o -> o.getSchoolId() + ";" + o.getIsSendSchool()))), ArrayList::new)
            );
            ArrayList<DepartBasicModel> departListFinal1 = departListFinal.stream().collect(
                    collectingAndThen(
                            toCollection(() -> new TreeSet<>(Comparator.comparing(DepartBasicModel::getId))), ArrayList::new)
            );
            ArrayList<UserPageModel> userListFinal1 = userListFinal.stream().collect(
                    collectingAndThen(
                            toCollection(() -> new TreeSet<>(Comparator.comparing(UserPageModel::getId))), ArrayList::new)
            );


            //分组  根据某一字段分组
            Map<Integer, List<JiTuanAddressModel>> schoollistMap = schoolListFinal1.stream().distinct().collect(Collectors.groupingBy(JiTuanAddressModel::getSchoolId));
            Map<Integer, List<DepartBasicModel>> departlistMap = departListFinal1.stream().distinct().collect(Collectors.groupingBy(DepartBasicModel::getSchoolId));
            Map<Integer, List<UserPageModel>> userlistMap = userListFinal1.stream().distinct().collect(Collectors.groupingBy(UserPageModel::getSchoolId));