Java Stream：按键过滤列表组中的地图

Question

有一个列表（List

[
{
   "name": "Wall Street",
   "point" "Walls Street",
   "similarity" : "0.945"
},
{
   "name": "Wall Street",
   "point" "Walldd Street",
   "similarity" : "0.871
},
{
   "name": "Duck Street",
   "point" "Ducks duck",
   "similarity" : "0.765
},
{
   "name": "Duck Street",
   "point" "yelow duck",
   "similarity" : "0.563
}
...
]

如何过滤列表，通过name得到最高的similarity映射组，然后使用Java Stream组合成列表？ 结果示例为：

[
{
   "name": "Wall Street",
   "point" "Walls Street",
   "similarity" : 0.945
},

{
   "name": "Duck Street",
   "point" "Ducks duck",
   "similarity" : 0.765
}
...
]

ps：如果多张地图中有相同的similarity值，请将它们都保留在列表中。

初始代码：

    List<HashMap<String, String>> res = new ArrayList<>();

    HashMap<String, String> map1 = new HashMap<>();
    map1.put("name", "Wall Street");
    map1.put("point", "Walls Street");
    map1.put("similarity", "0.945");

    HashMap<String, String> map2 = new HashMap<>();
    map2.put("name", "Wall Street");
    map2.put("point", "Walldd Street");
    map2.put("similarity", "0.871");

    HashMap<String, String> map3 = new HashMap<>();
    map3.put("name", "Duck Street");
    map3.put("point", "Ducks duck");
    map3.put("similarity", "0.765");

    HashMap<String, String> map4 = new HashMap<>();
    map4.put("name", "Duck Street");
    map4.put("point", "yelow duck");
    map4.put("similarity", "0.563");

    res.add(map1);
    res.add(map2);
    res.add(map3);
    res.add(map4);

Answer 1

@Falah 提供的解决方案的一些更改

List<Map<String, String>> result = res.stream().collect(Collectors.groupingBy(map->map.get("name")))
                                .entrySet().stream().map(m -> m.getValue().stream()
                                        .max(Comparator.comparingDouble(s -> Double.parseDouble(s.get("similarity")))).get())
                                .collect(Collectors.toList());

1. 按名称分组
2. 从每个组中获取最大相似度值

Answer 2

先按名称分组，然后按最大相似度分组

        List<Map.Entry<String, Optional<HashMap<String, String>>>> result = res.stream()
               .collect(Collectors.groupingBy(
                       map -> map.get("name"),
                       Collectors.maxBy(Comparator.comparingDouble(o -> Double.parseDouble(o.get("similarity"))))
               )).entrySet().stream().toList();


        result.forEach((map) -> {
            System.out.print("Max similarity of  " + map.getKey() + " is : ");
            map.getValue().ifPresent(System.out::println);
        });