Get JSON in AsyncTask Android

Question

I'm trying to get JSON but I have to do it in AsyncTask , because I get this in logcat AndroidRuntime(18153): Caused by: android.os.NetworkOnMainThreadException.

Here is my code:

public class LatestAlbums extends Activity {

    TextView t;

    // url to make request
    private static String url = "www.example.com";

    // JSON Node names
    private static final String TAG_ALBUMS = "albums";
    private static final String TAG_ID = "id";
    private static final String TAG_NAME = "name";
    private static final String TAG_SINGER = "singer";
    private static final String TAG_GENRE = "genre";
    private static final String TAG_MIX = "mix";
    private static final String TAG_THUMB = "thumb";
    private static final String TAG_SONGS = "songs";
    private static final String TAG_SONG_TITLE = "song";
    private static final String TAG_SONG_ARTIST = "artist";
    private static final String TAG_SONG_MP3 = "mp3";
    private static final String TAG_SONG_MP4 = "mp4";
    private static final String TAG_SONG_THUMB = "thumb";

    // albums JSONArray
    JSONArray albums = null;
    JSONArray sngs = null;
    JSONObject objects = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.favorites);
        t = (TextView) findViewById(R.id.json);
        loadJSON();
    }

    public void loadJSON() {
        // Creating JSON Parser instance
        JSONParser jParser = new JSONParser();

        // getting JSON string from URL
        JSONObject json = jParser.getJSONFromUrl(url);

        try {
            // Getting Array of albums

            albums = json.getJSONArray(TAG_ALBUMS);
            sngs=json.getJSONArray(TAG_SONGS);
            // looping through All albums
            for (int i = 0; i < albums.length(); i++) {
                JSONObject c = albums.getJSONObject(i);

                // Storing each json item in variable
                String album_id = c.getString(TAG_ID);
                String album_name = c.getString(TAG_NAME);
                String album_singer = c.getString(TAG_SINGER);
                String album_genre = c.getString(TAG_GENRE);
                String album_thumb = c.getString(TAG_THUMB);

                // songs are again JSON Object
                for (int j = 0; i < sngs.length(); j++) {
                    JSONObject s = sngs.getJSONObject(j);
                    JSONObject songs = s.getJSONObject(TAG_SONGS);
                    String artist = s.getString(TAG_SONG_ARTIST);
                    String mp3 = s.getString(TAG_SONG_MP3);
                    String mp4 = s.getString(TAG_SONG_MP4);
                    String song_thumb = s.getString(TAG_SONG_THUMB);
                    String song_title = s.getString(TAG_SONG_TITLE);
                }
                Log.v("--", "Albums \n" + " " + album_id + " " + album_name
                        + " " + album_genre + " " + album_singer + " "
                        + album_thumb);
            }

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

    }

}

Can anybody please tell me how to do this?

Zar E Ahmer · Answer 1 · 2015-07-14T06:32:55.627

Best and easy way to read JSON and set it to the Adapter .

AsyncTask has three methods.

in PreExecute and PostExecute you can set any view Properties (As you are on Main UI Thread) but in doInBackground (operation other than interacting with UI goes here) it reads the JSON

package com.example.tabs;

import java.util.ArrayList;
import java.util.HashMap;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.Toast;

import com.example.adapters.CalendarAdapter;
import com.example.description.CalendarDescription;

public class Calendar extends Activity {

    String url = "Enter your URL here ";

    GetData data;

    ProgressDialog progressDialog;

    ListView list_of_calendar;

    ArrayList<HashMap<String, String>> list = new ArrayList<HashMap<String, String>>();

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.calendar);

        list_of_calendar = (ListView) findViewById(R.id.list_of_calendar);

        new GetData().execute();
        //new GetData(url).execute();//you can pass it like this and see comment in doInBackground

        //ListView listView = getListView();
        list_of_calendar.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) 
            {
                HashMap<String, String> map = list.get(position);               

                Intent intent = new Intent(Calendar.this, CalendarDescription.class);

                intent.putExtra("name", map.get("name"));

                intent.putExtra("date", map.get("date"));

                intent.putExtra("description", map.get("description"));

                startActivity(intent);


            }

        });
    }

    private class GetData extends AsyncTask<String, Void, JSONObject> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

            progressDialog = ProgressDialog.show(Calendar.this,
                    "", "");

        }

        @Override
        protected JSONObject doInBackground(String... params) {

            String response;

            try {

                HttpClient httpclient = new DefaultHttpClient();

                HttpPost httppost = new HttpPost(url);
                //HttpPost httppost = new HttpPost(params[0]);//you can also pass it and get the Url here. 

                HttpResponse responce = httpclient.execute(httppost);

                HttpEntity httpEntity = responce.getEntity();

                response = EntityUtils.toString(httpEntity);

                Log.d("response is", response);

                return new JSONObject(response);

            } catch (Exception ex) {

                ex.printStackTrace();

            }

            return null;
        }

        @Override
        protected void onPostExecute(JSONObject result) 
        {
            super.onPostExecute(result);

            progressDialog.dismiss();

            if(result != null)
            {
                try
                {
                    JSONObject jobj = result.getJSONObject("result");

                    String status = jobj.getString("status");

                    if(status.equals("true"))
                    {
                        JSONArray array = jobj.getJSONArray("data");

                        for(int x = 0; x < array.length(); x++)
                        {
                            HashMap<String, String> map = new HashMap<String, String>();

                            map.put("name", array.getJSONObject(x).getString("name"));

                            map.put("date", array.getJSONObject(x).getString("date"));

                            map.put("description", array.getJSONObject(x).getString("description"));

                            list.add(map);
                        }

                        CalendarAdapter adapter = new CalendarAdapter(Calendar.this, list);

                        list_of_calendar.setAdapter(adapter);
                    }
                }
                catch (Exception e) 
                {
                    e.printStackTrace();
                }
            }
            else
            {
                Toast.makeText(Calendar.this, "Network Problem", Toast.LENGTH_LONG).show();
            }
        }

    }
}

Edit

the code is for the url

http://www.socialgeolocate.com/DayCare/webservices/Get_calender.php?

Which would be an example of the json structure for that parse? I dont understand the "result", "status" and "data" strings. Thanks. — Karlo A. López, Jul 13 '15 at 17:23
Karlo see my updated answer. I have attached the link from where i am getting data. — Zar E Ahmer, Jul 14 '15 at 06:33
Thanks nepster, I have the doubt of how to get a clean json array (I mean , without dictionariess or JSONObjects before) but know I know that i should use JSONArray in the whole asyncTask instead of JSONObject, thats why I wanted to see the JSON of that read, thanks again.. — Karlo A. López, Jul 14 '15 at 15:41
Your example URL returns just text/html Why not to return contents using the application/json MIME-type? — jap1968, Dec 19 '15 at 08:21
right now i have no access to it. jap 1968 but you can view the json by adding google chrome jsonview plugin. — Zar E Ahmer, Dec 27 '15 at 16:23

Trinimon · Accepted Answer · 2013-03-30T15:20:46.973

5

Load your JSON object in background (doing the network operation) and process the result in the UI thread, i.e.:

URL requestUrl = "...";

new AsyncTask<URL, Void, JSONObject>() {

    @Override
    protected Boolean doInBackground(URL... urls) {
        loadJSON(url);
    }

    @Override
    protected void onPostExecute(JSONObject jsonData) {
        try {
            // Getting Array of albums

            albums = json.getJSONArray(TAG_ALBUMS);
            sngs=json.getJSONArray(TAG_SONGS);
            // looping through All albums

            etc.
    }
}.execute(requestUrl);


public void loadJSON(URL url) {
    // Creating JSON Parser instance
    JSONParser jParser = new JSONParser();

    // getting JSON string from URL
    JSONObject json = jParser.getJSONFromUrl(url);

    return json;
}

Check out this for more information.

Cheers!

edited Mar 30 '13 at 15:20

answered Mar 30 '13 at 15:14

Trinimon

13,839
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when I put it in my code I got lots of errors. Do I have to put this in a new class – Darko Petkovski Mar 30 '13 at 15:23
1

I just tried to give you a rough idea. There still are some thing to do, of course. But the idea should be clear, isn't it? P.s. if you get stuck somewhere, paste your updated code and add what's not working – Trinimon Mar 30 '13 at 15:29
1

@BozidarPrcovski Have you read about `ASyncTask` at developers.android.com ? If so is the case, there shouldn't be any problem while implementing it. – Arslan Ali Mar 30 '13 at 15:31

score 0 · Answer 3 · edited May 23 '17 at 12:00

0

This is how a asynctask works

do your parsing in

doInBackground()

and do the thing with retrieved data in

onPostExecute()

edited May 23 '17 at 12:00

Community

1
1

answered Mar 30 '13 at 15:11

Ercan

3,705
1
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Get JSON in AsyncTask Android

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