How to just read wanted data from JSON in Java & Android

Question

I asked a similar question few days ago about how i could read just wanted data from JSON file in AngularJS, but i gonna do this job in java in android, so I have a problem in reading and logging JSON file like this,:

{
"results" : [
  {
     "address_components" : [
        {
           "long_name" : "277",
           "short_name" : "277",
           "types" : [ "street_number" ]
        },
        {
           "long_name" : "Bedford Avenue",
           "short_name" : "Bedford Ave",
           "types" : [ "route" ]
        },
        {
           "long_name" : "Williamsburg",
           "short_name" : "Williamsburg",
           "types" : [ "neighborhood", "political" ]
        },
        {
           "long_name" : "Brooklyn",
           "short_name" : "Brooklyn",
           "types" : [ "sublocality_level_1", "sublocality", "political" ]
        },
        {
           "long_name" : "Kings County",
           "short_name" : "Kings County",
           "types" : [ "administrative_area_level_2", "political" ]
        },
        {
           "long_name" : "New York",
           "short_name" : "NY",
           "types" : [ "administrative_area_level_1", "political" ]
        },
        {
           "long_name" : "United States",
           "short_name" : "US",
           "types" : [ "country", "political" ]
        },
        {
           "long_name" : "11211",
           "short_name" : "11211",
           "types" : [ "postal_code" ]
        }
     ],
     "formatted_address" : "277 Bedford Ave, Brooklyn, NY 11211, USA",
     "geometry" : {
        "location" : {
           "lat" : 40.714232,
           "lng" : -73.9612889
        },
        "location_type" : "ROOFTOP",
        "viewport" : {
           "northeast" : {
              "lat" : 40.7155809802915,
              "lng" : -73.9599399197085
           },
           "southwest" : {
              "lat" : 40.7128830197085,
              "lng" : -73.96263788029151
           }
        }
     },
     "place_id" : "ChIJd8BlQ2BZwokRAFUEcm_qrcA",
     "types" : [ "street_address" ]
  },
  ],
  "status" : "OK"
  }

I know in Java/android we have 2 types (JSON array and JSON object and these represents with [ and { ). I just need the name of city, not all of these data. How could I log just wanted object row.

I tried this code but that doesn't work:

protected String doInBackground(String... params) {


    HttpURLConnection connection = null;
    BufferedReader reader = null;

    try {
        URL url = new URL(params[0]);
        connection = (HttpURLConnection) url.openConnection();
        connection.connect();
        InputStream stream = connection.getInputStream();
        reader = new BufferedReader(new InputStreamReader(stream));
        StringBuffer buffer = new StringBuffer();
        String line = "";
        String data = "";
        while ((line = reader.readLine()) != null) {
            buffer.append(line+"\n");
            Log.d("Response: ", "> " + line);
                try {
                    JSONObject  jsonRootObject = new JSONObject(line);


                    JSONArray jsonArray = jsonRootObject.optJSONArray("results");
                    for(int i=0; i < jsonArray.length(); i++){
                        JSONObject jsonObject = jsonArray.getJSONObject(i);
                        String name = jsonObject.optString("formatted_address").toString();


                        data = name;
                    }

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

        }

        return data.toString();


    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (connection != null) {
            connection.disconnect();
        }
        try {
            if (reader != null) {
                reader.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;
}

-------------- Edit: i used this code:

JSONObject  jsonRootObject = new JSONObject(newData);

            JSONArray jsonArray = jsonRootObject.optJSONArray("results");
            for(int i=0; i <=1 ; i++){
                JSONObject jsonObject = jsonArray.getJSONObject(i);

                data = jsonObject.getString("address_components");
            }

and now i have another json string like this:

        [
        {
           "long_name" : "277",
           "short_name" : "277",
           "types" : [ "street_number" ]
        },
        {
           "long_name" : "Bedford Avenue",
           "short_name" : "Bedford Ave",
           "types" : [ "route" ]
        },
        {
           "long_name" : "Williamsburg",
           "short_name" : "Williamsburg",
           "types" : [ "neighborhood", "political" ]
        },
        {
           "long_name" : "Brooklyn",
           "short_name" : "Brooklyn",
           "types" : [ "sublocality_level_1", "sublocality", "political" ]
        }]

how i can access to value of the "long_name" key of object(n) ?

score 2 · Accepted Answer · answered Jun 03 '16 at 14:46

2

change your try block to

        while ((line = reader.readLine()) != null) {
            buffer.append(line+"\n");
        }

        Log.d("Response: ", "> " + line);
        try {
             JSONObject  jsonRootObject = new JSONObject(line);

             JSONArray jsonArray = jsonRootObject.optJSONArray("results");
             for(int i=0; i < jsonArray.length(); i++){
             JSONObject jsonObject = jsonArray.getJSONObject(i);
             data = jsonObject.getString("formatted_address")

          }

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

Now you will have valid string to JSONObject conversion since previously you parsing incomplete string in while loop which isnt valid json.

answered Jun 03 '16 at 14:46

Shubhank

21,721
8
65
83

I have no idea why my app will crashs – Mort Jun 03 '16 at 15:18
@MortezaAghili crash should be coming in logcat, can you update your question with that log ? – Shubhank Jun 03 '16 at 15:20
I added the message, i think its cuz when i use virtual device, right? but in my real device it crashs too – Mort Jun 03 '16 at 15:29
maybe you can join [chat](http://chat.stackoverflow.com/rooms/26424/iosandroidchaosoverflow) to solve it faster. – Shubhank Jun 03 '16 at 15:32
take a look at edited section of my question please. thank you – Mort Jun 03 '16 at 21:55

score 0 · Answer 2 · answered Jun 03 '16 at 14:46

0

You need to wait until all the input has been read. In other words, all of the JSON Handling code should be out of the while loop.

answered Jun 03 '16 at 14:46

Amit

1,111
1
8
14

score 0 · Answer 3 · answered Jun 03 '16 at 14:52

You can use the JSON library to parse this object:

public class JsonValue {
    public static void main(String[] args) throws JSONException {
        String jsonString = "{ \"field1\" : \"value1\", \"city\" : \"New York\", \"address\" : \"address1\" }";
        JSONObject jsonObject = new JSONObject(jsonString);
        String city = jsonObject.getString("city");
        System.out.println(city);
     }
}

score 0 · Answer 4 · answered Jun 03 '16 at 14:57

0

Or you can use GSON:

Gson gson = new Gson();
Type type = new TypeToken<List<AddressComponents>>() {}.getType();
List<AddressComponents> fromJson = gson.fromJson(json, type);

http://www.vogella.com/tutorials/JavaLibrary-Gson/article.html

answered Jun 03 '16 at 14:57

user3816621

134
7

score 0 · Answer 5 · answered Jun 03 '16 at 15:08

0

First create this two models:

public class ResultModel{
    public string formatted_address;
}

public class ResponseModel{
    public List<ResultModel> results;
}

then get your addresses with:

Gson gson = new Gson();
ResponseModel response = gson.fromJson(json, ResponseModel.class);

response.results // this is your list of "formatted addresses"

Can be iterated with for cycle or used anywhere. All other json will be ignored.

make sure to include in your gradle:

compile 'com.google.code.gson:gson:2.4'

answered Jun 03 '16 at 15:08

Stepan Maksymov

2,618
19
31

I have no idea why the app crashs – Mort Jun 03 '16 at 16:24
to know this always post your code ) according to crash info you probably has not enabled location service or you not requested rights for it – Stepan Maksymov Jun 03 '16 at 16:37
i have 2 AsyncTask which work with user current location, the first work fine, its get the json from api and work fine, but the second( which i asked about here) didn't works and the app crashs after run this task – Mort Jun 03 '16 at 16:56
application crashes not here, it crashes on get location your location object is probably null but you want to get latitude from it. – Stepan Maksymov Jun 03 '16 at 17:24
Could you please take a look at this question : http://stackoverflow.com/questions/37620221/from-2-asynctask-which-works-with-user-location-just-one-works-in-java-android – Mort Jun 03 '16 at 17:25

How to just read wanted data from JSON in Java & Android

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