详解Java实现JSONArray转Map的三种实现方式

[
    {
        "flagType": 1,
        "flagIcon": "1.jpg"
    },
    {
        "flagType": 2,
        "flagIcon": "2.jpg"
    },
    {
        "flagType": 3,
        "flagIcon": "3.jpg"
    },
    {
        "flagType": 4,
        "flagIcon": "4.jpg"
    }
]

{
    1:"1.jpg",
    2:"2.jpg",
    3:"3.jpg",
    4:"4.jpg"
}

JSONArray jsonArray= new JSONArray();
//填充初始数据，此处过程省略
List<JSONObject> jsonObjectList = jsonArray.toJavaList(JSONObject.class);
Map<Integer, String> map = jsonObjectList.stream().filter(Objects::nonNull).collect(Collectors.toMap(item -> item.getInteger("flagType"), item -> item.getString("flagIcon")));

JSONArray jsonArray= new JSONArray();
//填充初始数据，此处过程省略
Map<Integer, String> map = jsonArray.stream().filter(Objects::nonNull)
                .collect(Collectors.toMap(
                        object -> {
                            JSONObject item = (JSONObject) object;
                            return item.getInteger("flagType");
                        },
                        object -> {
                            JSONObject item = (JSONObject) object;
                            return item.getString("flagIcon");
                        }
                ));

Map<Integer, String> flagIconMap = new HashMap<>();
 
JSONArray jsonArray= new JSONArray();
//填充初始数据，此处过程省略
if (jsonArray != null && !jsonArray.isEmpty()) {
    jsonArray.forEach(object -> {
        if (object == null) {
            return;
        }
        JSONObject jsonObject = (JSONObject) object;
        if (jsonObject.getInteger("flagType") == null) {
            return;
        }
        flagIconMap.put(jsonObject.getInteger("flagType"),jsonObject.getString("flagIcon"));
    });
}