private class ReadJSONFeedTask extends AsyncTask <String, Void, String>
	{
		protected String doInBackground(String...urls)
		{
			Log.d("JSON",  "number of surveys in feed 3");
			return readJSONFeed(urls[0]);
		}

		protected void onPostExecute(String result)
		{
			try{
				Log.d("JSON", "Result file - " + result);
				JSONArray jsonArray = new JSONArray(result);

				for(int i=0; i<ksonArray.length(); i++)
				{
					Log.d("JSON", "result file - " + 1);
					JSONObject jsonObject3 = jsonArray.getJSONObject(i);
					Log.d("data json", jsonArray.getJSONObject(i).toString());

					ab = new ArrayBook(jsonObject3.getString("book_id"), jsonObject3.getString("title"), jsonObject3.getString("author_code"));
					Toast.makeText(getBaseContext(), ab.getAuthor().toString(), Toast.LENGTH_SHORT).show();
					dataBook.add(ab);
				}

				adapter = new CustomAdapter (getApplicationContext (), dataBook);
				lvi.setAdapter(adapter);

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

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

			dataBook = new ArrayList<ArrayBook>();

			setContentView(R.layout.activity_main);
			lvi = (ListView) findViewById(R.id.list);

			Log.d("JSON", "number of surveys in feed");
			new ReadJSONFeedTask().execute("http://yustinuswidya.com/senghansun.json");
			Log.d("JSON", "number of surveys in feed 2");

			adapter = new CustomAdapter(getApplicationContext(), dataBook);
			lvi.setAdapter(adapter);
		}
	}