Как реализовать

Помогите , немогу реализовать Json код . Мне нужно взять данные но немогу понять как .... можете мне прописать этот код.....

Json лежит в папке assets/json/dannye.json

Вот реализатор класс

public class Utility {

public static String getFileContent(Context context) throws IOException {
    InputStream inputStream = context.getAssets().open("json/dannye.json");
    StringBuilder rawContentBuilder = new StringBuilder();
    byte[] buffer = new byte[1024];
    inputStream.read(buffer);
    do {
        String chunk = new String(buffer);
        rawContentBuilder.append(chunk);
    } while (inputStream.read(buffer) > 0);
    return rawContentBuilder.toString();
  }
}

А вот так я его беру из класса Фрагмент

private List<Dannye> initData() {

    try {
        String rawJson = Utility.getFileContent(getContext());
        JSONObject(rawJson).getJSONArray(groupName);
        JSONArray group = new JSONObject(rawJson).getJSONArray("d_1_18");
        Log.e(TAG, "initializeHeroes: " + group);
        list = new ArrayList<>();
        for (int i = 0; i < group.length(); i++) {
            JSONObject hero = group.getJSONObject(i);

            String hour = hero.getString("hour");
            String lesson = hero.getString("lesson");
            String spes = hero.getString("spes");
            String aut = hero.getString("aut");
            Dannye dannye = new Dannye(hour, lesson, spes, aut);
            list.add(dannye);
        }
    } catch (IOException e) {
        System.out.println("NO bATTLE.JSON!!!");
    } catch (JSONException e) {
        System.out.println("JSON MALFoRMEEEED!!");
    }
    return list;
   }

Как мне прописать код чтоб взять данные у меня ошибка NullpointExeption

Вот собственно Json

  {
   "d_1_18": {
    "Monday": [{
        "hour": "08:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "09:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "11:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "12:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "14:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "15:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "17:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    }],
    "Tuesday": [{
        "hour": "08:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "09:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "11:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "12:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "14:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "15:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "17:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    }]
    },
     "d_2_18": {
    "Monday": [{
        "hour": "08:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "09:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "11:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "12:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "14:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "15:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "17:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    }],
    "Tuesday": [{
        "hour": "08:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "09:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "11:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "12:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "14:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "15:30",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    },{
        "hour": "17:00",
        "lesson": "Informatika",
        "spes": "prog",
        "aut": "105"
    }]
}

}