Intent myIntent = new Intent(MainActivity.this , CheckUpdateService.class);
    AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
    PendingIntent pendingIntent = PendingIntent.getService(MainActivity.this, 0, myIntent, 0);
    Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, 12);
    calendar.set(Calendar.MINUTE, 00);
    calendar.set(Calendar.SECOND, 00);
    alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), 24*60*60*1000 , pendingIntent);  //set repeating every 24 hours

public class CheckAppsUpdateService extends Service {

private GetJSONData update_notif_service;

public CheckAppsUpdateService() {
}

@Override
public IBinder onBind(Intent intent) {
    //throw new UnsupportedOperationException("Not yet implemented");
    return null;
}

@Override
public void onStart(Intent intent, int startId) {
    super.onStart(intent, startId);
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    ConnectionStatusDetector csd = new ConnectionStatusDetector(this);

    if (csd.isConnectingToInternet()) {
        try {
            // execute an asycntask here for getting Json data from server
        }catch (Exception e){
            Log.e("Update service error", "nothing");
        }
    }
    return super.onStartCommand(intent, flags, startId);
}

@Override
public void onDestroy() {
    super.onDestroy();
    if (update_notif_service != null && update_notif_service.getStatus() == AsyncTask.Status.RUNNING) {
        update_notif_service.cancel(true);
    }
}
}