How to get the data in a array from URL

Question

I am trying to get data from a JSON URL. Of course by AsyncTask. But the problem is the JSON file does not have Object. It is an array. JSON URL and api website

Can someone tell me how to create a JSONArray and JSONObject for this JSON file?!

Here is what I have done which makes the app stop working

//URL to get JSON Array
private static String url = "http://api.worldbank.org/countries/ir?format=json";

//JSON Node Names 
private static final String TAG_OBJ = "user";
private static final String NAME = "name";
private static final String CAPITALCITY = "capitalCity";
    .
    .
    .
    class GetJSONTask extends AsyncTask<String, Void, JSONObject> {


    protected JSONObject doInBackground(String... urls) {
        // Creating new JSON Parser
        JSONParser jParser = new JSONParser();

        // Getting JSON from URL
        JSONObject json = JSONParser.getJson(url);

        return json;
    }
    protected void onPostExecute(JSONObject json) {
        //Getting JSON Array
        try {
            user = json.getJSONArray(TAG_OBJ);
            JSONObject c = user.getJSONObject(0);

            //Stroing JSON item in a Variable
            String name = c.getString(NAME);
            String capitalCity = c.getString(CAPITALCITY);

            //Importing TextView
            final TextView view1 = (TextView)findViewById(R.id.name);
            final TextView view2 = (TextView)findViewById(R.id.capitalCity);

            //Set JSON Data in TextView
            view1.setText(name);
            view2.setText(capitalCity);

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

Answer 1

Change your MainActivity.java like below,

public class MainActivity extends Activity {

// URL to get JSON Array
private static String url = "http://api.worldbank.org/countries/ir?format=json";

// JSON Node Names
private static final String TAG_NAME = "name";
private static final String TAG_CAP_City = "capitalCity";
JSONArray responseArray = null;

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

    setContentView(R.layout.activity_main);

    new GetJSONTask().execute();



}
class GetJSONTask extends AsyncTask<String, Void, String> {

    @Override
    protected String doInBackground(String... arg0) {
        // Creating new JSON Parser
        JSONParser jParser = new JSONParser();

        // Getting JSON from URL
        String json = jParser.getJSONFromUrl(url);
        return json;
    }
    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);

        try {
            // Getting JSON Array
            responseArray = new JSONArray(result);
            JSONArray parsedArray=responseArray.getJSONArray(1);
            JSONObject c = parsedArray.getJSONObject(0);

            // Storing JSON item in a Variable
            String name = c.getString(TAG_NAME);
            String email = c.getString(TAG_CAP_City);

            // Importing TextView
            // final TextView uid = (TextView)findViewById(R.id.uid);
            final TextView name1 = (TextView) findViewById(R.id.name);
            final TextView email1 = (TextView) findViewById(R.id.email);

            // Set JSON Data in TextView
            // uid.setText(id);
            name1.setText(name);
            email1.setText(email);

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

}

}

Also change JSONParser.java

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    public String getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();           

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        /*// try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }*/

        // return JSON String
        return json;

    }
}

Answer 2

Please note that i have used Strict Policy. You continue using Async Task and put my code in there. Here is my Code related to your requirement .

JsonParser.Java

    package com.example.test;

import android.os.StrictMode;
import android.util.Log;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
static JSONArray jArray = null;
// constructor
public JSONParser() {

}

public JSONArray getJSONFromUrl(String url) {

    // Making HTTP request
    try {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

        StrictMode.setThreadPolicy(policy);
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        json = sb.toString();
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }

    // try parse the string to a JSON object
    try {
        jArray = new JSONArray(json);
     //   jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
    return jArray;

}
}

MainActivity.java

        package com.example.test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.Menu;

public class MainActivity extends Activity {
    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Making HTTP request
        String url = "http://api.worldbank.org/countries/ir?format=json";
        JSONParser jParser = new JSONParser();

        // Getting JSON from URL
        JSONArray json = jParser.getJSONFromUrl(url);
        try {
            JSONArray json2 = json.getJSONArray(1); // Your second Array in your json

            for(int i=0;i<json2.length();i++){

                JSONObject c = json2.getJSONObject(i);
                // Storing  JSON item in a Variable
                String name = c.optString("name","");
                String capitalCity = c.optString("capitalCity","");

            }

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


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

Answer 3

Use JSON Array . Here is my code :-

String url = "http://api.androidhive.info/contacts/";
    JSONParser jParser = new JSONParser();

    // Getting JSON from URL
    JSONObject json = jParser.getJSONFromUrl(url);
    try {
        // Getting JSON Array
        JSONArray begin = json.getJSONArray("contacts");
        JSONObject c = begin.getJSONObject(0);

        // Storing  JSON item in a Variable
        String id = c.getString("id");
        String name = c.getString("name");
        String size = c.getString("email");

Put this in your Async

Answer 4

if(i<jArray.length()) {
         JSONObject json_obj = jArray.getJSONObject(i);   //get array object
         name = json_obj.getString("your tag name");        fetch item here
    }