List＜Map＞转Map＜String,List＞

╰+攻爆jí腚メ 2022-12-23 12:29 253阅读 0赞

1、问题

我现在拿到的数据是下图形式，那我现在需要以cubicleId为主键，重新组list

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTM0MTE1_size_16_color_FFFFFF_t_70][]

处理后的数据，这是我想要的数据

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTM0MTE1_size_16_color_FFFFFF_t_70 1][]

2、解决

Map newMap = grouping(listParams,"cubicleId");

private static Map<String, Object> grouping(List<Map> list, String key) {
            // 使用TreeMap存放元素并排序
            Map<String, Object> newMap = new TreeMap<>(new Comparator<String>() {
                @Override
                public int compare(String o1, String o2) {
                    return o2.compareTo(o1);
                }
            });
            list.stream().forEach(m -> {
                List<Object> l = new ArrayList<>();
                l.add(m);
                newMap.replace(m.get(key).toString(), l);
                if (m.containsKey(key)) {
                    if (newMap.containsKey(m.get("cubicleId").toString())){
                        l.add(m);
                        newMap.replace(m.get(key).toString(), l);
                    }else {
                        l.clear();
                        l.add(m);
                        newMap.put(m.get(key).toString(), l);
                    }
            }});
            return newMap;
        }

3、补充

List<Map>根据Map的某个字段去重

listParams = listParams.stream().collect(Collectors.collectingAndThen(
                        Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(p -> p.get("cubicleId").toString()))),
                        ArrayList::new));

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTM0MTE1_size_16_color_FFFFFF_t_70]: /images/20221120/a87bd6a5f5bf4480876724bebb2dbdc0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTM0MTE1_size_16_color_FFFFFF_t_70 1]: /images/20221120/9ede2d9dce7e43da8baae5fb5873aca1.png