Muestra con éxito mis datos del servicio web JSON en listview, pero quiero agregar Asyntask ... Donde puedo poner el código Asyntask en mi código ...

Este mi código para mostrar datos en vista de lista

public class Jadwal_remix extends ListActivity {
String v_date;
JSONArray r_js = null;
ArrayList<HashMap<String, String>> myArray = new ArrayList<HashMap<String,String>>();
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.main);





    String status ="";
    String date = "";
    String result = "";
    String url = "http://10.0.2.2/remix/view_list.php";
    JSONParser jParser = new JSONParser();
    JSONObject json = jParser.AmbilJson(url);
    try
    {
        r_js = json.getJSONArray("view_list");

        for (int i =0; i < r_js.length(); i++)
        {
            String my_array = "";
            JSONObject ar = r_js.getJSONObject(i);
            status = ar.getString("st");
            date = ar.getString("date");
            result = ar.getString("result");

            if (status.trim().equals("er"))
            {
                my_array += "Sorry "+result;
                HashMap<String, String> map = new HashMap<String, String>();
                map.put("result", my_array);
                myArray.add(map);
            }
            else
            {
                my_array += "Date : "+date+" "+"Result : "+result;
                HashMap<String, String> map = new HashMap<String, String>();
                map.put("result", my_array);
                myArray.add(map);
            }

        }
    }
    catch (JSONException e) 
    {
         e.printStackTrace();
    }
    adapter_listview();

}

public void adapter_listview() {

    ListAdapter adapter = new SimpleAdapter(this, jadwalRemix,R.layout.my_list,new String[] { "result"}, new int[] {R.id.txtResult});
    setListAdapter(adapter);
}
}

Y este JSONParser

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

public JSONObject AmbilJson(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) {
            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;

}
 }

Por favor, ayúdame, donde puedo poner código para Asyntask ... Muchas gracias ...

Ok, obtengo un código de muestra, y mi código ahora es como este

public class Jadwal_remix extends ListActivity {
String v_date;
JSONArray r_js = null;
ArrayList<HashMap<String, String>> myArray = new ArrayList<HashMap<String,String>>();
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.main);

private class myProses extends AsyncTask<Void, Void, Void> {
    ProgressDialog dialog;

    protected void onPreExecute() {
        dialog = ProgressDialog.show(Jadwal_remix.this, "", "Loading... Please wait", true);

    }
protected Void doInBackground(Void... params) {



    String status ="";
    String date = "";
    String result = "";
    String url = "http://10.0.2.2/remix/view_list.php";
    JSONParser jParser = new JSONParser();
    JSONObject json = jParser.AmbilJson(url);
    try
    {
        r_js = json.getJSONArray("view_list");

        for (int i =0; i < r_js.length(); i++)
        {
            String my_array = "";
            JSONObject ar = r_js.getJSONObject(i);
            status = ar.getString("st");
            date = ar.getString("date");
            result = ar.getString("result");

            if (status.trim().equals("er"))
            {
                my_array += "Sorry "+result;
                HashMap<String, String> map = new HashMap<String, String>();
                map.put("result", my_array);
                myArray.add(map);
            }
            else
            {
                my_array += "Date : "+date+" "+"Result : "+result;
                HashMap<String, String> map = new HashMap<String, String>();
                map.put("result", my_array);
                myArray.add(map);
            }

        }
    }
    catch (JSONException e) 
    {
         e.printStackTrace();
    }
    return null;
protected void onPostExecute(Void unused) {
        adapter_listview();
        dialog.dismiss();
    }

}

public void adapter_listview() {

    ListAdapter adapter = new SimpleAdapter(this, jadwalRemix,R.layout.my_list,new String[] { "result"}, new int[] {R.id.txtResult});
    setListAdapter(adapter);
}
}

Tengo problemas cuando el servidor está muerto, aún se está cargando ... ¿cómo puedo mostrar el mensaje ej .: no puedo conectarme al servidor ...?