将嵌套的 JSON 转换为嵌套的 HashMap

Question

How can we convert the nested json to nested hashmap without creating the pojo classes.

{
  "IdeskFields": [
    {
      "fieldName": "CLIENT_TAX_TYPE_ID",
      "values": [
        {
          "key": "dataType",
          "value": "Integer"
        },
        {
          "key": "CLIENT_TAX_TYPE_VAT",
          "value": "2"
        },
        {
          "key": "CLIENT_TAX_TYPE_GST",
          "value": "8"
        },
        {
          "key": "CLIENT_TAX_TYPE_Tax",
          "value": "9"
        }
      ]
    }
  ]
}

Need to be converted to Map<String, Map<String, String>> map

Answer 1

You can use ObjectMapper from jackson .

Map map = new ObjectMapper().readValue(jsonString, HashMap.class);

A map will be an instance of

HashMap<String, ArrayList<LinkedHashMap<String, ArrayList<LinkedHashMap<String, String>>>>>

Answer 2

If you can use the Gson library then you can do something like this

Gson gson = new Gson();

Map map = gson.fromJson(str, Map.class);

But that would leave to the library to determine the type of values.

Therefore better way to use Gson#fromJson(String, Type) something like below:

Type mapType = new TypeToken<Map<String, List<Map<String, Object>>>>() {}.getType();

Map<String, List<Map<String, Object>>> map = gson.fromJson(str, mapType);

I use Object as inner map value type because your values are different ie string and list of another map.