Blog Reader App problem... Not able to get JSON data in the log.

package com.divyansh.blogreader;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

public class MainListActivity extends ListActivity {

    protected String[] mDayNames;
    public static final int NUMBER_OF_POSTS = 20;
    public static final String TAG = MainListActivity.class.getSimpleName();
    protected JSONObject mBlogData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        if(isNetworkAvailable()){
            GetBlogPostsTask getBlogPostTask = new GetBlogPostsTask();
            getBlogPostTask.execute();


        }else{
                    Toast.makeText(this, "Network is unavailable", Toast.LENGTH_LONG).show();
                }




        //  Toast.makeText(this, message, Toast.LENGTH_LONG).show();


    }

    private boolean isNetworkAvailable() {
        ConnectivityManager manager = (ConnectivityManager) 
                getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo networkInfo = manager.getActiveNetworkInfo();

        boolean isAvailable = false;
        if(networkInfo != null && networkInfo.isConnected()){
            isAvailable = true;
        }
        return isAvailable;
    }

    public void updateList() {
        if(mBlogData ==  null){
        // TODO: Handle error 
        }else{
            try {
                Log.d(TAG,mBlogData.toString(2));
            } catch (JSONException e) {
                Log.d(TAG,"Exception caught!",e);
            }
        }
    }

    @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_list, menu);
        return true;

    }

    private class GetBlogPostsTask extends AsyncTask<Object, Void, JSONObject>{

        @Override
        protected JSONObject doInBackground(Object... arg0) {
            int responseCode = -1;
            JSONObject jsonResponse = null;

            try{
                URL blogFeedURL = new URL("http://blog.teamtreehouse.com/api/get_recent_summary/?count=" + NUMBER_OF_POSTS);
                HttpURLConnection connection = (HttpURLConnection) blogFeedURL.openConnection();
                connection.connect();

                responseCode = connection.getResponseCode();
                Log.i(TAG, "Response is" + responseCode);
                if(responseCode == HttpURLConnection.HTTP_OK){
                    InputStream inputStream = connection.getInputStream();
                    Reader reader = new InputStreamReader(inputStream);
                    int contentLength = connection.getContentLength();
                    char[] charArray = new char[contentLength];
                    reader.read(charArray);
                    String responseData = new String(charArray);

                    jsonResponse = new JSONObject(responseData);

                }           
                else{
                Log.i(TAG, "Unsuccessful HTTP Response Code: " + responseCode);
                }               
            }
            catch(MalformedURLException e){
                Log.e(TAG,"URL Exception caught");
            }
            catch(IOException e){
                Log.e(TAG,"IO Exception caught");
            }           
            catch(Exception e){
                Log.e(TAG,"Exception caught");
            }

            Log.i(TAG,"Response" + responseCode);
            return jsonResponse;
        }

        @Override
        protected void onPostExecute(JSONObject result){
            mBlogData = result;
            updateList();
        }
    }




     @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            // Handle action bar item clicks here. The action bar will
            // automatically handle clicks on the Home/Up button, so long
            // as you specify a parent activity in AndroidManifest.xml.
            int id = item.getItemId();
            if (id == R.id.action_settings) {
                return true;
            }
            return super.onOptionsItemSelected(item);
        }

    }