Question

I would like to get “lat” and “lng” from my JSON file and add to one array that keeps GeoPoint. I was trying to do it like that but it is not working for me :

protected List<GeoPoint> JsonArray(){
        List<GeoPoint> endp = new ArrayList<GeoPoint>();

        try{
        JSONObject obj = new JSONObject(json);
        JSONArray steps = obj.getJSONArray("routes");
        for(int i=0;i<steps.length();i++){
            JSONObject temp = steps.getJSONObject(i);
            JSONObject ele = temp.optJSONObject("steps").optJSONObject("end_location");
            ele.getJSONObject("lat");
            ele.getJSONObject("lng");

            double lat = Double.parseDouble(ele.getJSONObject("lat").toString());
            double lng = Double.parseDouble(ele.getJSONObject("lng").toString());
            endp.add(new GeoPoint((int)(lat *1E6),(int)(lng * 1E6)));

        }



        }catch (JSONException e) {
            // TODO: handle exception
        }
        return endp;
    }

Here’s a part of how looks my JSON file:

{
       "routes" : [
          {
             "bounds" : {
                "northeast" : {
                   "lat" : 41.87999000000001,
                   "lng" : -87.615020
                },
                "southwest" : {
                   "lat" : 29.74674000000001,
                   "lng" : -95.361220
                }
             },
             "copyrights" : "Dane do Mapy ©2013 Google",
             "legs" : [
                {
                   "distance" : {
                      "text" : "1 085 mil",
                      "value" : 1746457
                   },
                   "duration" : {
                      "text" : "16 godz. 39 min",
                      "value" : 59955
                   },
                   "end_address" : "1362 Chenevert Street, Houston, Teksas 77003, Stany Zjednoczone",
                   "end_location" : {
                      "lat" : 29.750110,
                      "lng" : -95.36016000000001
                   },
                   "start_address" : "138-230 South Columbus Drive, Chicago, Illinois 60601, Stany Zjednoczone",
                   "start_location" : {
                      "lat" : 41.87999000000001,
                      "lng" : -87.62075000000002
                   },
                   "steps" : [
                      {
                         "distance" : {
                            "text" : "338 stóp",
                            "value" : 103
                         },
                         "duration" : {
                            "text" : "1 min",
                            "value" : 9
                         },
                         "end_location" : {
                            "lat" : 41.88090,
                            "lng" : -87.62069000000001
                         },
                         "html_instructions" : "Kieruj się \u003cb\u003eS Columbus Dr\u003c/b\u003e na \u003cb\u003epółnoc\u003c/b\u003e w stronę \u003cb\u003eE Monroe St\u003c/b\u003e",
                         "polyline" : {
                            "points" : "}tr~FtlxuOuA@w@@QMUA"
                         },
                         "start_location" : {
                            "lat" : 41.87999000000001,
                            "lng" : -87.62075000000002
                         },
                         "travel_mode" : "DRIVING"
                      },
                      {
                         "distance" : {
                            "text" : "0,2 mil",
                            "value" : 266
                         },
                         "duration" : {
                            "text" : "1 min",
                            "value" : 33
                         },
                         "end_location" : {
                            "lat" : 41.88086000000001,
                            "lng" : -87.61750000000001
                         },
                         "html_instructions" : "Skręć \u003cb\u003ew prawo\u003c/b\u003e w \u003cb\u003eE Monroe St\u003c/b\u003e",
                         "polyline" : {
                            "points" : "szr~FhlxuO?SAyA?_B@yA?iBAaB?WBE@C@A?C?A@A?C?y@?_@"
                         },
                         "start_location" : {
                            "lat" : 41.88090,
                            "lng" : -87.62069000000001
                         },
                         "travel_mode" : "DRIVING"
                      },
                      {
                         "distance" : {
                            "text" : "2,0 mil",
                            "value" : 3186
                         },
                         "duration" : {
                            "text" : "3 min",
                            "value" : 180
                         },
                         "end_location" : {
                            "lat" : 41.85320,
                            "lng" : -87.61470000000001
                         },
                         "html_instructions" : "Skręć \u003cb\u003ew prawo\u003c/b\u003e w \u003cb\u003eU.S. 41 S\u003c/b\u003e",
                         "polyline" : {
                            "points" : "kzr~FjxwuOpMOZ@`PO|ACvDC@?lDCZAfMGjAA`@Av@?^?P?N@P@j@LRFNDRJRHZRb@\\b@^nAjA@@JJXXb@b@z@v@RRp@`@RLr@Xn@Np@J`A@bBOp@Kv@K@?@?@A@?@?@?@?PEvBWxB]fDq@xA]jF_BTIj@QpGuBd@OBAf@SrDyAPGNG@AVKbA_@~@]|@]z@Y`F{AtCy@fHyB"
                         },
                         "start_location" : {
                            "lat" : 41.88086000000001,
                            "lng" : -87.61750000000001
                         },
                         "travel_mode" : "DRIVING"
                      },
                      {
                         "distance" : {
                            "text" : "0,4 mil",
                            "value" : 581
                         },
                         "duration" : {
                            "text" : "1 min",
                            "value" : 30
                         },
                         "end_location" : {
                            "lat" : 41.848390,
                            "lng" : -87.614670
                         },
                         "html_instructions" : "Zjedź \u003cb\u003eInterstate 55 S\u003c/b\u003e w kierunku \u003cb\u003eSaint Louis\u003c/b\u003e",
                         "polyline" : {
                            "points" : "omm~FzfwuOVDPAN?VGlBk@b@M@?JEDAVI`A[dBi@`A[z@UPGZGf@E\\Ab@@VDJBHBTFTHRJPNRNLL\\f@NXLTP\\BF"
                         },
                         "start_location" : {
                            "lat" : 41.85320,
                            "lng" : -87.61470000000001
                         },
                         "travel_mode" : "DRIVING"
                      },

Does anyone knows how can I do it in other way?

Answer 1

Your variable JSONArray steps = obj.getJSONArray("routes"); does not represent the “steps” part of the JSON object, but rather the “routes” part.

Also, you have skipped some of the levels in the JSON hierarchy. With the given JSON, you would need the following steps to traverse the JSON (I have omitted looping over the different arrays, except for the routes array)

JSONArray routes = obj.getJSONArray("routes");
for(int i=0; i < routes.length(); i++){
    // Grab the first route
    JSONObject route = routesArray.getJSONObject(i);
    // Take all legs from the route
    JSONArray legs = route.getJSONArray("legs");
    // Grab first leg
    JSONObject leg = legs.getJSONObject(0);
    // Take all steps from the leg
    JSONArray steps = leg.getJSONArray("steps");
    // Grab first step
    JSONObject step = steps.getJSONObject(0);

    JSONObject endLocation = step.getJSONObject("end_location");
    String lat = endLocation.getString("lat");
    String lng = endLocation.getString("lng");

Reference: JSON parsing of Google Maps API in Android App