如何在主 class - JSON 中获取嵌套数组值到 POJO

Question

I have a JSON like this:

{
   "types":[
      {
         "slot":1,
         "type":{
            "name":"grass",
            "url":"https://pokeapi.co/api/v2/type/12/"
         }
      },
      {
         "slot":2,
         "type":{
            "name":"poison",
            "url":"https://pokeapi.co/api/v2/type/4/"
         }
      }
   ]
}

I need only names of types, so I'd like to have something like this:

public class MainClass {

    private List<String> types;
}

I want to avoid creating of nested classes. How can I get this result?

Answer 1

The simplest way is to convert your JSON to map and retrieve from there the List and from each element get Map and get the value by key type. Here is the link to a question on how to parse your JSON . The rest should be trivial

Answer 2

Using Jackson, you can do:

ArrayNode types = objectMapper.readTree(jsonStr).withArray("types");

List<String> typeNames = IntStream.range(0, types.size())
        .mapToObj(types::get)
        .map(json -> json.get("type")
            .get("name")
            .asText())
        .collect(Collectors.toList());

or using org.json , you can do:

JSONArray jsonArray = new JSONObject(jsonStr).getJSONArray("types");

List<String> typeNames = IntStream.range(0, jsonArray.length())
        .mapToObj(jsonArray::getJSONObject)
        .map(json -> json.getJSONObject("type")
                .getString("name"))
        .collect(Collectors.toList());

Both return the output:

[grass, poison]