How to read JSON file with Arrays and Objects in Java

Question

I'm trying to read a file which is fetched from Opentdb and access data from only specific keys.

I've tried all of the given methods which includes GSON and Json Simple but ended up having errors.

Here's my JSON:

    {
  "response_code": 0,
  "results": [
    {
      "category": "Sports",
      "type": "multiple",
      "difficulty": "easy",
      "question": "Which of the following sports is not part of the triathlon?",
      "correct_answer": "Horse-Riding",
      "incorrect_answers": [
        "Cycling",
        "Swimming",
        "Running"
      ]
    },
    {
      "category": "Sports",
      "type": "multiple",
      "difficulty": "easy",
      "question": "Which English football club has the nickname \u0026#039;The Foxes\u0026#039;?",
      "correct_answer": "Leicester City",
      "incorrect_answers": [
        "Northampton Town",
        "Bradford City",
        "West Bromwich Albion"
      ]
    },

I want to access only category, difficulty, question , correct_answer and incorrect_answers .

If you don't mind using a third party lib I suggest using Jackson, you can find a tutorial here https://www.baeldung.com/java-json — Dmytro Grynets, Jun 14 '19 at 16:13
Thank you but the best solution I found was use of Pojos with gson. it worked like a charm. — Rai Ansar, Jun 16 '19 at 18:41

score 0 · Answer 1 · answered Jun 14 '19 at 17:27

excample for you

try {
        URL resource = App.class.getClassLoader().getResource("info.json");
        System.out.println(resource.toString());
        FileReader reader = new FileReader(resource.getFile());

        // Read JSON file
        Object obj = jsonParser.parse(reader);

        JSONArray infoList = (JSONArray) obj;
        System.out.println(infoList);

        Information i = new Information();

        List<Information> info = i.parseInformationObject(infoList);

        saveInformation(info);
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();

    } catch (IOException e) {
        e.printStackTrace();
    } catch (ParseException e) {
        e.printStackTrace();
    }

and

List<Information> parseInformationObject(JSONArray infoList) {
    List<Information> in = new ArrayList<>();

    infoList.forEach(emp -> {

        JSONObject info = (JSONObject) emp;

        String id = info.get("id").toString();
        String state = info.get("state").toString();
        String type = null;
        if (info.get("type") != null) {
            type = info.get("type").toString();
        }
        String host = null;
        if (info.get("host") != null) {
            host = info.get("host").toString();
        }
        long timestamp = (long) info.get("timestamp");

        in.add(new Information(id, state, type, host, timestamp));

    });
    return in;
}

How to read JSON file with Arrays and Objects in Java

1 Answers1