listmap根据某字段进行合并

龙谷情Sinoam

于 2022-09-09 14:28:00 发布

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文章标签： java mybatis spring mysql jvm

本文链接：https://blog.youkuaiyun.com/qq_36012282/article/details/126784860

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    public List<Map<String, Object>> mergeResult(List<Map<String, Object>> m1, List<Map<String, Object>> m2, String key) {
        m1.addAll(m2);
        Set<String> set = new HashSet<>();
        List<Map<String, Object>> resultList = m1.stream().collect(Collectors.groupingBy(o -> {
            // 暂存所有key
            set.addAll(o.keySet());
            return o.get(key);
        })).entrySet().stream().map(o -> {
            // 合并
            Map<String, Object> map = o.getValue().stream().flatMap(m -> {
                return m.entrySet().stream();
            }).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (a, b) -> b));
            // 为没有key的赋值0
            set.stream().forEach(k -> {
//                if (!map.containsKey(k))
//                    map.put(k, 0);
            });
            return map;
        }).sorted((map1,map2)->{
            return map1.get(key).toString().compareTo(map2.get(key).toString());
        }).collect(Collectors.toList());
        return resultList;

    }