Java - How can i read json file and put values into array

Question

I have this JSON file called city.list.json, containing objects like these:

{
"id": 707860,
"name": "Hurzuf",
"country": "UA",
"coord": {
  "lon": 34.283333,
  "lat": 44.549999
}}

How can I put name's value into array?

This is the code I've tried:

String name = null;

    JSONArray jsonArr = new JSONArray("[JSON String]");
    ArrayList<Data> dataList = new ArrayList<>();
    for (int i = 0; i < jsonArr.length(); i++) {

        JSONObject jsonObj = jsonArr.getJSONObject(i);
        Data data = new Data();

        data.name = jsonObj.getString("name");


        dataList.add(data);
    }

But it gives me errors on data saying "Constructor Data in class Data cannot applied to given types"

I've tried the code in this topic stackoverflow.com/questions/38052384/… — Daniele
– Daniele, Commented Dec 19, 2017 at 15:59

Neeraj Jain · Accepted Answer · 2017-12-19 16:19:41Z

-1

You can use GSON library to achieve this task:

String input = yourSampleJson;
Gson gson = new Gson();
Map<String,Object> inputPojo = new HashMap<>();
inputPojo = gson.fromJson(input, inputPojo.class); // This map now contains the representation of your JSON.

I generally prefer having a POJO class which represents your JSON structure something as :

Class DanielePojo {
  Integer id;
  String name;
  String country;
  Coord coord; // This is another class similar to this POJO which is represented as Object in your JSON
 // Then your getters and setters
}

Then you can convert JSON into Pojo object directly without having a MAP as an intermediate object.

DanielePojo pojo = new GSON.fromJSON(input,DanielePojo.class);

edited Dec 19, 2017 at 16:19

answered Dec 19, 2017 at 15:45

Neeraj Jain

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