Android : Json object cannot be converted to jsonarray in google map android

In my code i want to show marker in google map v2 using JSON. but I have a problem when i run this code application can open map but can't show maker and in logcat show error json object cannot be converted to jsonarray. And This is my code

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ProgressDialog;
import android.net.ParseException;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.util.Log;
import android.widget.Toast;
import app.ex.phmeter.list.JSONAsyncTask;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL; 
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class map  extends FragmentActivity{

        Arraydata adapter;
        final int RQS_GooglePlayServices = 1;
        private GoogleMap myMap;
        private String userid;
        private String pHdata, address, latitude, longitude;
        Double lat;
        Double lng;
        final ArrayList<HashMap<String, String>> MyArrList = new ArrayList<HashMap<String, String>>();
        HashMap<String, String> map;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.map);
            FragmentManager myFragmentManager = getSupportFragmentManager();
            SupportMapFragment mySupportMapFragment = (SupportMapFragment) myFragmentManager
            .findFragmentById(R.id.map);
            myMap = mySupportMapFragment.getMap();
            showMarker();
     }
     public void showMarker() {
         new LoadContentFromServer().execute();
        }

         class LoadContentFromServer extends AsyncTask<String, Integer, String> {

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

         String url = "http://phm.umr-lab.com/retrieve.php";
         return getJSONUrl(url);
        }

         public String getJSONUrl(String url) {
         StringBuilder str = new StringBuilder();
         HttpClient client = new DefaultHttpClient();
         HttpGet httpGet = new HttpGet(url);
         try {
         HttpResponse response = client.execute(httpGet);
         StatusLine statusLine = response.getStatusLine();
         int statusCode = statusLine.getStatusCode();
         if (statusCode == 200) {
        HttpEntity entity = response.getEntity();
         InputStream content = entity.getContent();
         BufferedReader reader = new BufferedReader(
         new InputStreamReader(content));
         String line;
         while ((line = reader.readLine()) != null) {
         str.append(line);
         }
        } else {
         Log.e("Log", "Failed to download file..");
         }
         } catch (ClientProtocolException e) {
         e.printStackTrace();
         } catch (IOException e) {
         e.printStackTrace();
         }
         return str.toString();
         }

         @Override
         protected void onPostExecute(String result) {
         try {
             JSONArray data = new JSONArray(result);
         for (int i = 0; i < data.length(); i++) {
         JSONObject c = data.getJSONObject(i);

         map = new HashMap<String, String>();
         map.put("Datalocat", c.getString("Datalocat"));
         map.put("pHdata", c.getString("pHdata"));
         map.put("Latitude", c.getString("Latitude"));
         map.put("Longitude", c.getString("Longitude"));
         MyArrList.add(map);

         pHdata = map.get("pHdata");
         address = map.get("Datalocat");
         latitude = map.get("Latitude");
         longitude = map.get("Longitude");
         lat = Double.parseDouble(latitude);
         lng = Double.parseDouble(longitude);

         try {
         myMap.addMarker(new MarkerOptions()
         .position(new LatLng(lat, lng))
         .title(userid).snippet(address));
         } catch (Exception e) {
         e.printStackTrace();
        }
        }
        } catch (JSONException e) {
         e.printStackTrace();
        }
        }
         }
}