Asynctask zum Überprüfen ob Internet verfügbar ist

public class NetworkAvailability extends AsyncTask<Context, Boolean, Boolean> {

    Context mContext;

    /*------------------------Prüfen ob Internet verfügbar----------------------*/
    private static boolean isNetworkAvailable() {
        ConnectivityManager connectivityManager = (ConnectivityManager) ListViewActivity.getAppContext().getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        if (activeNetworkInfo != null && activeNetworkInfo.isConnectedOrConnecting()) {
            Log.i("Netzwerkstatus: ", "Netzwerk-Verbindung verfügbar");
            return true;
        }
        return false;

    }

public NetworkAvailability(Context mContext) {
        this.mContext = mContext;
    }

    public NetworkAvailability() {
    }

    @Override
    protected Boolean doInBackground(Context... params) {
        if (isNetworkAvailable()) {
            try {
                HttpURLConnection urlc = (HttpURLConnection) (new URL("http://www.google.de").openConnection());
                urlc.setRequestProperty("User-Agent", "Test");
                urlc.setRequestProperty("Connection", "close");
                urlc.setConnectTimeout(1500);
                try {
                    urlc.connect();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                //i ist 200 bei Internetverbindung
                int i = urlc.getResponseCode();
                return (i == 200);
            } catch (IOException e) {
                Log.e("IsInternetAccessible: ", "Konnte Internetverbindung nicht prüfen");
            }
        } else {
            Log.d("IsInternetAccessible:", "Internet nicht verfügbar");
        }
        return false;
    }

}

            if (networkAvailability.execute()) {
                XMLParser parser = new XMLParser();
                String xml = parser.getXMLFromUrl("http://XXXXX/XX.xml");
                Document doc = parser.getDomElement(xml);

                NodeList nl = doc.getElementsByTagName(KEY_SYSTEM);

                for (int i = 0; i < nl.getLength(); i++) {

                    // Neue HashMap erstellen
                    HashMap<String, String> map = new HashMap<String, String>();
                    Element e = (Element) nl.item(i);

                    // Jedes Kind-Knoten zur HashMap
                    map.put(KEY_UUID, parser.getValue(e, KEY_UUID));
                    map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
                    map.put(KEY_JOBTITLE, parser.getValue(e, KEY_JOBTITLE));
                    map.put(KEY_JOBINFO, parser.getValue(e, KEY_JOBINFO));
                    map.put(KEY_IMAGE, parser.getValue(e, KEY_IMAGE));

                    //Hashmap zur ArrayList hinzufügen
                    menuItems.add(map);
                }
            } else {
                Log.i("doInBackground:", "Keine Internet-Verbindung");
                return null;
            }