如何在 json 对象响应中解析 json 数组？

Question

Iwant to access a jsonArray data in a jsonObjet response code that comes from server. here is my response json

{
    event_id: "32",
    event_title: "امیر",
    event_description: "تست امیر",
    event_image: "2_1550507094.jpg",
    event_hikers_amount: "9",
    event_private: "0",
    event_date_start: "17/2/2019",
    event_date_end: "21/2/2019",
    event_time_start: "21:54",
    event_time_end: "12:54",
    event_locations_array: 
        "[
            {"latitude":37.58728984572849,"longitude":45.10016608983278},
            {"latitude":37.57651702299841,"longitude":45.0880378112197},
            {"latitude":37.5753956777439,"longitude":45.1045374199748},         
            {"latitude":37.564077382844964,"longitude":45.094508975744255},
            {"latitude":37.55829758877768,"longitude":45.08105669170619},
            {"latitude":37.53919984571198,"longitude":45.09874418377876}
        ]",
    event_latitude_location: "37.587289845728",
    event_longitude_location: "45.100166089833",
    event_status: "1",
    event_users_id: "2"
}

I want to parse "event_locations_array" and what what i done :

@Override
        protected void onPostExecute(String result) {

            try {
                JSONObject jsonObject = new JSONObject(result);

                description = jsonObject.getString("event_description");
                people_joined = jsonObject.getString("event_hikers_amount");
                date_start = jsonObject.getString("event_date_start");
                date_end = jsonObject.getString("event_date_end");
                time_start = jsonObject.getString("event_time_start");
                time_end = jsonObject.getString("event_time_end");
                privacy = jsonObject.getString("event_private");

                JSONArray jsonArray = jsonObject.getJSONArray("event_locations_array");
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject points = jsonArray.getJSONObject(i);
                    JSONObject lat = points.getJSONObject("latitude");
                    JSONObject lang = points.getJSONObject("longitude");
                }

                setTextView();

            } catch (JSONException e) {
                e.printStackTrace();
            }

        }

here i can't take that jsonArray. what i did wrong here let me know . I'm a little confused thanks in advance

Answer 1

Fast solution

If you can not change the JSON generation, simply use this code:

@Override
protected void onPostExecute(String result) {

try {
  JSONObject jsonObject = new JSONObject(result);

  description = jsonObject.getString("event_description");
  people_joined = jsonObject.getString("event_hikers_amount");
  date_start = jsonObject.getString("event_date_start");
  date_end = jsonObject.getString("event_date_end");
  time_start = jsonObject.getString("event_time_start");
  time_end = jsonObject.getString("event_time_end");
  privacy = jsonObject.getString("event_private");

  // 1 - fix string to array conversion
  JSONArray jsonArray = new JSONArray(jsonObject.getString("event_locations_array"));
  for (int i = 0; i < jsonArray.length(); i++) {
    JSONObject points = jsonArray.getJSONObject(i);
    // 2 - the fields as double
    double lat = points.getDouble("latitude");
    double lang = points.getDouble("longitude");
  }

  setTextView();

  } catch (JSONException e) {
    e.printStackTrace();
  }
}

Detailed solution

There are two errors:

1. The event_locations_array : "[[{"latitude":37.58728984572849].." contains a string. For the value that it's contains I think it must be generated as array (without the initial and final ")

2. After fix the first problem, you are trying to extract as object the properties latitude and longitude , but they are attributes. So change in your code:

for (int i = 0; i < jsonArray.length(); i++) {
  JSONObject points = jsonArray.getJSONObject(i);
  JSONObject lat = points.getJSONObject("latitude");
  JSONObject lang = points.getJSONObject("longitude");
}

With

for (int i = 0; i < jsonArray.length(); i++) {
  JSONObject points = jsonArray.getJSONObject(i);
  double lat = points.getDouble("latitude");
  double lang = points.getDouble("longitude");
}

Answer 2

To get Values of event_locations_array use following code:

JSONArray jsonArray = jsonResponse.getJSONArray("event_locations_array");
    for (int i=0; i<jsonArray.length(); i++) {
        JSONObject jsonObject = jsonArray.getJSONObject(i);
        String latitude = jsonObject.getString("latitude");
        String longitude = jsonObject.getString("longitude");
    }