on Android

Android GPS-Location

I wrote this LocationHelper class to get the gps (or wifi) location.

public class LocationHelper {

    private MyLocation location;

    Context context;

    Timer timer;
    LocationManager lm;
    boolean gps_enabled=false;
    boolean network_enabled=false;
    ILocation activity;

    private LocationHelper(){
    }

    public LocationHelper(Context context){
        this();

        this.context = context;
        location = new MyLocation();
    }

    public LocationHelper(Context context, ILocation activity){
        this(context);

        this.activity = activity;
    }

    LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer.cancel();
            gotLocation(location);
            // gps will keep going
            lm.removeUpdates(locationListenerNetwork);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    LocationListener locationListenerNetwork = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer.cancel();
            gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerGps);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    class GetLastLocation extends TimerTask {
        @Override
        public void run() {
             lm.removeUpdates(locationListenerGps);
             lm.removeUpdates(locationListenerNetwork);

             Location net_loc=null, gps_loc=null;
             if(gps_enabled){
                 gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
             }
             if(network_enabled){
                 net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
             }

             //if there are both values use the latest one
             if(gps_loc!=null && net_loc!=null){
                if(gps_loc.getTime() > net_loc.getTime()){
                     gotLocation(gps_loc);
                }else{
                     gotLocation(net_loc);
                }
                return;
             }

             if(gps_loc!=null){
                 gotLocation(gps_loc);
                 return;
             }
             if(net_loc!=null){
                 gotLocation(net_loc);
                 return;
             }

             gotLocation(null);
        }
    }

    private void gotLocation(Location newLocation){
        if(newLocation != null){
            if(activity != null){
                activity.updateDirectionOnObjects(newLocation);
            }

            location.setLatitude(newLocation.getLatitude());
            location.setLongitude(newLocation.getLongitude());
        }
    }

    public MyLocation getLocation() {
        return location;
    }

    public void register() {
        if(lm==null){
            lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        }

        //exceptions will be thrown if provider is not permitted.
        try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);}catch(Exception ex){}
        try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);}catch(Exception ex){}

        //don't start listeners if no provider is enabled
        if(gps_enabled || network_enabled){
            if(gps_enabled){
                lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 12000, 0, locationListenerGps);
            }
            if(network_enabled){
                lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
            }

            timer=new Timer();
            timer.schedule(new GetLastLocation(), 20000);
        }
    }

    public void unregister() {
        lm.removeUpdates(locationListenerGps);
        lm.removeUpdates(locationListenerNetwork);
    }
}

MyLocation is a simple model class:

public class MyLocation {
    private double latitude;
    private double longitude;

    public double getLatitude() {
        return latitude;
    }
    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }
    public double getLongitude() {
        return longitude;
    }
    public void setLongitude(double longitude) {
        this.longitude = longitude;
    }
}

ILocation is a interface that can be implemented if you want a feedback when the location is found:

public interface ILocation {
    public void updateDirectionOnObjects(Location location);
}

To use it you will have to create a LocationHelper object:

private LocationHelper locationHelper;

In the onCreate-Method:

locationHelper = new LocationHelper(this);
//If you want to use the feedback-method:
//locationHelper = new LocationHelper(this,this);
//Note: you will have to implement ILocation for this to work!

In the onResume-Method (not onCreate!) register the listener:

locationHelper.register();

In the onPause-Method unregister the listener:

locationHelper.unregister();

If you didn’t implement ILocation you can get the current Location with following call:

locationHelper.getLocation();