blogreader has stoped

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);
    try {
        JSONArray jsonPosts=mBlogData.getJSONArray("posts");
        JSONObject jsonPost=jsonPosts.getJSONObject(position);
        String blogUrl=jsonPost.getString("url");
       //Intent  intent=new Intent(Intent.ACTION_VIEW);
        Intent  intent=new Intent(this,BlogViewActivity.class);
        intent.setData(Uri.parse(blogUrl));
        startActivity(intent);


    } catch (JSONException e) {
        logException(e);
    }
}

private void logException(Exception e) {
    Log.e(TAG, "Exception caught!", e);
}

private boolean isNetworkAvalaible() {
    boolean isAvailable=false;
    ConnectivityManager manager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo=manager.getActiveNetworkInfo();
    if(networkInfo!=null && networkInfo.isConnected()){
        isAvailable=true;
    }
    return isAvailable;
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.list, menu);
    return true;
}
private void handleBlogResponse() {
    mProgressBar.setVisibility(View.INVISIBLE);
    if(mBlogData==null){
        updateDisplayForError();
    }else{
        try {
            JSONArray jsonPosts=mBlogData.getJSONArray("posts");
            ArrayList<HashMap<String, String>> blogPosts=new ArrayList<HashMap<String, String>>();

            //mBlogPostTitles=new String[jsonPosts.length()];
            for(int i=0;i<jsonPosts.length();i++){
                JSONObject post=jsonPosts.getJSONObject(i);
                String title=post.getString(KEY_TITLE);
                title= Html.fromHtml(title).toString();
                String author=post.getString(KEY_AUTHOR);
                author= Html.fromHtml(author).toString();
                HashMap<String, String> blogPost=new HashMap<String, String>();
                blogPost.put(KEY_TITLE,title);
                blogPost.put(KEY_AUTHOR,author);
                blogPosts.add(blogPost);


            }
            String[] keys={KEY_TITLE,KEY_AUTHOR};
            int[] ids={android.R.id.text1,android.R.id.text2};
            SimpleAdapter adapter=new SimpleAdapter(this,blogPosts,android.R.layout.simple_list_item_2,keys,ids);
            //ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mBlogPostTitles);
            setListAdapter(adapter);
            //Log.d(TAG,mBlogData.toString(2));
        } catch (JSONException e) {
            logException(e);
        }
    }
}

private void updateDisplayForError() {
    AlertDialog.Builder builder=new AlertDialog.Builder(this);
    builder.setTitle(getString(R.string.title));
    builder.setMessage(getString(R.string.error_message));
    builder.setPositiveButton(android.R.string.ok,null);
    AlertDialog dialog=builder.create();
    dialog.show();
    TextView emptyTextView= (TextView) getListView().getEmptyView();
    emptyTextView.setText(R.string.no_items);
}


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

    @Override
    protected JSONObject doInBackground(Object... strings) {
        int responsecode=-1;
        JSONObject jsonResponse=null;
        try {
            URL blogFeedURL = new URL("http://blog.teamtreehouse.com/api/get_recent_summary/?count="+NUMBER_OF_POST);
            HttpURLConnection connection= (HttpURLConnection) blogFeedURL.openConnection();
            connection.connect();
            responsecode=connection.getResponseCode();
            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);
               /* String status=jsonResponse.getString("status");
                JSONArray jsonPosts=jsonResponse.getJSONArray("posts");
                for(int i=0;i<jsonPosts.length();i++){
                    JSONObject jsonPost=jsonPosts.getJSONObject(i);
                    String title=jsonPost.getString("title");

                }
                //Log.v(TAG,responseData);*/
            }else {
                Log.i(TAG, "Unsuccessful responseCode: " + responsecode);
            }
        }catch (MalformedURLException e){
            logException(e);
        }catch (IOException e){
            logException(e);
        }catch(Exception e){
            logException(e);
        }
        return jsonResponse;
     }

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

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