JSON Parsing in Android

Here is source code of the Program to Demonstrate Parsing a Json Object in Android. The program is successfully compiled and run on a Windows system using Eclipse Ide. The program output is also shown below.

In this program we initiate a HTTPS connection and using this connection we get a json object which we save in as JsonOBject and then we parse this JsonObject forming Json array and Json Object at every iteration.

Here we are calculating the total fare between two metro stations by getting a Json Object from the url specified, the output of which is shown in the screen.U must notice that in the following code an Async task is used to get json object , this is because the json object that u are getting is a network operation that u can’t operate in the main thread , u have to schedule in the background , and thus the Async task does this.

Main Activity

package com.example.json_app;
 
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
 
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;
 
public class MainActivity extends Activity {
 
    // URL to get JSON Array
    private static String url = "http://evaluate.rome2rio.com/api/1.2/json/Search?key=fWAL2WvM&oName=Dwarka+Delhi&dName=Hauz+Khas+Delhi";
 
    JSONObject json = null;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Creating new JSON Parser
        final JSONParser jParser = new JSONParser();
 
        // Getting JSON from URL
        final TextView text = (TextView) findViewById(R.id.text);
 
        new AsyncTask<Void, Void, Void>() {
 
            @Override
            protected Void doInBackground(Void... params) {
                json = jParser.getJSONFromUrl(url);
                return null;
            }
 
            @Override
            protected void onPostExecute(Void result) {
                super.onPostExecute(result);
                double tot_price = 0;
                try {
                    JSONArray routes = json.getJSONArray("routes");
 
                    for (int i = 0; i < routes.length(); i++) {
 
                        JSONObject obj = routes.getJSONObject(i);
                        String name = obj.getString("name");
                        if (name.contains("Metro")) {
                            System.out.println(obj.get("distance"));
 
                            // System.out.println(obj.get("segments"));
                            JSONArray segemnts = obj.getJSONArray("segments");
 
                            for (int j = 0; j < segemnts.length(); j++) {
                                JSONObject seg = segemnts.getJSONObject(j);
                                String name1 = seg.getString("kind");
                                if (name1.equals("train")) {
                                    String name2 = seg.getString("vehicle");
 
                                    if (name2.equals("Metro")) {
                                        System.out.println(seg
                                                .getString("sPos"));
                                        JSONArray iten = seg
                                                .getJSONArray("itineraries");
                                        for (int k = 0; k < iten.length(); k++) {
                                            JSONObject it = iten
                                                    .getJSONObject(k);
                                            for (int h = 0; h < it.length(); h++) {
                                                JSONArray legs = it
                                                        .getJSONArray("legs");
                                                JSONObject leg = legs
                                                        .getJSONObject(h);
                                                JSONArray hops = leg
                                                        .getJSONArray("hops");
                                                for (int o = 0; o < hops
                                                        .length(); o++) {
                                                    JSONObject hop = hops
                                                            .getJSONObject(o);
                                                    System.out
                                                            .println(hop
                                                                    .getString("sName")
                                                                    + "   "
                                                                    + hop.getString("tName"));
                                                    JSONObject iprice = hop
                                                            .getJSONObject("indicativePrice");
                                                    System.out
                                                            .println(iprice
                                                                    .getString("nativePrice"));
                                                    tot_price += Double
                                                            .parseDouble(iprice
                                                                    .getString("nativePrice"));
                                                }
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
 
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
 
                text.setText("Total Price :" + Double.toString(tot_price));
            }
        }.execute();
 
    }
 
}

Json Parser

package com.example.json_app;
 
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.JSONException;
import org.json.JSONObject;
 
import android.util.Log;
 
public class JSONParser {
 
    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";
 
    // constructor
    public JSONParser() {
 
    }
 
    public JSONObject 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) {
                Log.i("Tag",line);
                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 jObj;
 
    }
}

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