Question

I’m trying to resolve a small problem:

mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 120000, 0, mLocationListener);

So I assumed that mLocationListener should wait for 2 mainutes before calling it’s onLocationChanged method. However, the method is called right after I send geo fix updates to emulator, every time I do it. Did I misunderstand the android developers guide, and do I have to to use timers or anything similar for organizing update rate I need?

Answer 1

Well after some research and meditation 🙂 I’ve come up with something like this: a service that can run in two modes (depending on the listenPeriod variable): 1) simply process coordinates once and shut self down afterwards (listenPeriod=0); 2) and process coordinates with specified rate (listenPeriod>0) until the service will be shut down.

                        GPSTracer.listenPeriod = 120000;

                        comp = new ComponentName(context.getPackageName(), GPSTracer.class.getName());
                        GPSTracer.iGPSTracer = new Intent(context, GPSTracer.class.getClass());

                        GPSTracer.iGPSTracer.setComponent(comp);
                        service=context.startService(GPSTracer.iGPSTracer);

So I have to initialize the listenPeriod variable before I start my service. And the service part looks like this:

public class GPSTracer extends Service {

public static Intent iGPSTracer;

public static volatile Location mLocation = null;

public static volatile LocationListener mLocationListener = null;

public static LocationManager mLocationManager = null;

public static long listenPeriod = 0;

Timer mTimer = null;


Handler mHandler = new Handler(){
    @Override
    public void handleMessage(Message msg) {
        if(msg.arg1 == 1)
        {
            if(GPSTracer.mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER))
            {
                GPSTracer.mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 120000, 100, GPSTracer.mLocationListener);
            }
            else if(GPSTracer.mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER))
            {
                GPSTracer.mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 120000, 100, GPSTracer.mLocationListener);

            }
            else
            {
                List<NameValuePair> gpsData = new ArrayList<NameValuePair>();
                gpsData.add(new BasicNameValuePair("Error", "No location provider"));
                stopSelf();
            }
        }
        else if(msg.arg1 == 0)
        {
            GPSTracer.mLocationManager.removeUpdates(GPSTracer.mLocationListener);
        }
    }; 
};

TimerTask selfStopTask = new TimerTask() {

    @Override
    public void run() {
        stopSelf();

    }
};

TimerTask mTimerTask = new TimerTask() {

    @Override
    public void run() {
                    //Message mMessage = new Message();
                    //mHandler.sendMessage(mMessage);
        if(mLocation == null)
        {
            mLocation = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            if(mLocation == null)
            {
                mLocation = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

            }
        }
        if(mLocation != null)
        {
            List<NameValuePair> gpsData = new ArrayList<NameValuePair>();
            gpsData.add(new BasicNameValuePair("Latitude", (new Double(mLocation.getLatitude())).toString()));
            gpsData.add(new BasicNameValuePair("Longitude", (new Double(mLocation.getLongitude())).toString()));
            gpsData.add(new BasicNameValuePair("Provider", mLocation.getProvider()));
        }
        else
        {
            List<NameValuePair> gpsData = new ArrayList<NameValuePair>();
            gpsData.add(new BasicNameValuePair("Error", "Location is unknown"));
        }
    }
};

@Override
public void onCreate() {    
    mLocationManager = (LocationManager)getSystemService(LOCATION_SERVICE);
    mLocationListener = new GPSListener(getApplicationContext());

};

@Override
public void onStart(Intent intent, int startId) {

    Message mMessage = new Message();
    mMessage.arg1 = 1;
    mHandler.sendMessage(mMessage);

    if(listenPeriod == 0)
    {
        mTimer = new Timer("GPSTask");
        mTimer.schedule(mTimerTask, 0);
        mTimer.schedule(selfStopTask, 60000);
    }
    else if(listenPeriod>0)
    {
        mTimer = new Timer("GPSTask");
        mTimer.schedule(mTimerTask, 0, listenPeriod);
    }
};

@Override
public void onDestroy() {
    Message mMessage = new Message();
    mMessage.arg1 = 0;
    mHandler.sendMessage(mMessage);
            //GPSTracer.mLocationManager.removeUpdates(GPSTracer.mLocationListener);
    iGPSTracer = null;
    mTimer.cancel();
    mTimerTask.cancel();
    mTimer = null;
    mTimerTask = null;
    mLocationListener = null;
    mLocationManager = null;
};

@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}

}

and implementation of LocationListener:

public class GPSListener implements LocationListener{

   Context context;
   public GPSListener(Context appContext) {
       context = appContext;
}

   @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onLocationChanged(Location location) {
        //GPSTracer.mLocationManager.removeUpdates(GPSTracer.mLocationListener);
        GPSTracer.mLocation = location;
    }

}

I hope it will help someone…)
P.S. thanks to Dave MacLean and EboMike!; and feel free to ask questions;)