What is the simplest and most robust way to get the user's current location on Android? – Dev

The best answers to the question “What is the simplest and most robust way to get the user's current location on Android?” in the category Dev.

QUESTION:

The LocationManager API on Android seems like it’s a bit of a pain to use for an application that only needs an occasional and rough approximation of the user’s location.

The app I’m working on isn’t really a location app per se, but it does need to get the user’s location in order to display a list of nearby businesses. It doesn’t need to worry about if the user is moving around or anything like that.

Here’s what I’d like to do:

  1. Show the user a list of nearby locations.
  2. Preload the user’s location so that by the time I need it in Activity X, it will be available.
  3. I don’t particularly care about accuracy or frequency of update. Just grabbing one location is sufficient as long as it’s not way off. Maybe if I want to be fancy I’ll update the location once every few mins or so, but it’s not a huge priority.
  4. Work for any device as long as it has either a GPS or a Network Location provider.

It seems like it shouldn’t be that hard, but it appears to me that I have to spin up two different location providers (GPS and NETWORK) and manage each’s lifecycle. Not only that, but I have to duplicate the same code in multiple activities to satisfy #2. I’ve tried using getBestProvider() in the past to cut the solution down to just using one location provider, but that seems to only give you the best “theoretical” provider rather than the provider that’s actually going to give you the best results.

Is there a simpler way to accomplish this?

ANSWER:

After searching for best implementation how to get best precise user location I managed to combine all the best methods and come up with following class:

/**
 * Retrieve accurate location from GPS or network services. 
 * 
 *
 * Class usage example:
 * 
 * public void onCreate(Bundle savedInstanceState) {
 *      ...
 *      my_location = new MyLocation();
 *      my_location.init(main.this, locationResult);
 * }
 * 
 * 
 * public LocationResult locationResult = new LocationResult(){
 *      @Override
 *      public void gotLocation(final Location location){
 *          // do something
 *          location.getLongitude();
 *          location.getLatitude();
 *      }
 *  };
 */
class MyLocation{

    /**
     * If GPS is enabled. 
     * Use minimal connected satellites count.
     */
    private static final int min_gps_sat_count = 5;

    /**
     * Iteration step time.
     */
    private static final int iteration_timeout_step = 500;

    LocationResult locationResult;
    private Location bestLocation = null;
    private Handler handler = new Handler();
    private LocationManager myLocationManager; 
    public Context context;

    private boolean gps_enabled = false;

    private int counts    = 0;
    private int sat_count = 0;

    private Runnable showTime = new Runnable() {
    
         public void run() {
            boolean stop = false;
            counts++;
            System.println("counts=" + counts);
            
            //if timeout (1 min) exceeded, stop tying
            if(counts > 120){
                stop = true;
            }
            
            //update last best location
            bestLocation = getLocation(context);
            
            //if location is not ready or don`t exists, try again
            if(bestLocation == null && gps_enabled){
                System.println("BestLocation not ready, continue to wait");
                handler.postDelayed(this, iteration_timeout_step);
            }else{
                //if best location is known, calculate if we need to continue to look for better location
                //if gps is enabled and min satellites count has not been connected or min check count is smaller then 4 (2 sec)  
                if(stop == false && !needToStop()){
                    System.println("Connected " + sat_count + " sattelites. continue waiting..");
                    handler.postDelayed(this, iteration_timeout_step);
                }else{
                    System.println("#########################################");
                    System.println("BestLocation found return result to main. sat_count=" + sat_count);
                    System.println("#########################################");

                    // removing all updates and listeners
                    myLocationManager.removeUpdates(gpsLocationListener);
                    myLocationManager.removeUpdates(networkLocationListener);    
                    myLocationManager.removeGpsStatusListener(gpsStatusListener);
                    sat_count = 0;
                    
                    // send best location to locationResult
                    locationResult.gotLocation(bestLocation);
                }
            }
         }
    };
        
    /**
     * Determine if continue to try to find best location
     */
    private Boolean needToStop(){

        if(!gps_enabled){
                          return true;
                     }
          else if(counts <= 4){
                return false;
            }
            if(sat_count < min_gps_sat_count){
                //if 20-25 sec and 3 satellites found then stop
                if(counts >= 40 && sat_count >= 3){
                    return true;
                }
                return false;
            }
        }
        return true;
    }

    /**
     * Best location abstract result class
     */
    public static abstract class LocationResult{
         public abstract void gotLocation(Location location);
     }

    /**
     * Initialize starting values and starting best location listeners
     * 
     * @param Context ctx
     * @param LocationResult result
     */
    public void init(Context ctx, LocationResult result){
        context = ctx;
        locationResult = result;
    
        myLocationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
    
        gps_enabled = (Boolean) myLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
    
        bestLocation = null;
        counts = 0;
    
        // turning on location updates
        myLocationManager.requestLocationUpdates("network", 0, 0, networkLocationListener);
        myLocationManager.requestLocationUpdates("gps", 0, 0, gpsLocationListener);
        myLocationManager.addGpsStatusListener(gpsStatusListener);
    
        // starting best location finder loop
        handler.postDelayed(showTime, iteration_timeout_step);
    }

    /**
     * GpsStatus listener. OnChainged counts connected satellites count.
     */
    public final GpsStatus.Listener gpsStatusListener = new GpsStatus.Listener() {
        public void onGpsStatusChanged(int event) {
        
             if(event == GpsStatus.GPS_EVENT_SATELLITE_STATUS){
                try {
                    // Check number of satellites in list to determine fix state
                     GpsStatus status = myLocationManager.getGpsStatus(null);
                     Iterable<GpsSatellite>satellites = status.getSatellites();
                     
                     sat_count = 0;
                     
                     Iterator<GpsSatellite>satI = satellites.iterator();
                     while(satI.hasNext()) {
                         GpsSatellite satellite = satI.next();
                         System.println("Satellite: snr=" + satellite.getSnr() + ", elevation=" + satellite.getElevation());                         
                         sat_count++;
                     }
                } catch (Exception e) {
                    e.printStackTrace();
                    sat_count = min_gps_sat_count + 1;
                }
                 
                 System.println("#### sat_count = " + sat_count);
             }
         }
    };

    /**
     * Gps location listener.
     */
    public final LocationListener gpsLocationListener = new LocationListener(){
        @Override
         public void onLocationChanged(Location location){
        
        }
         public void onProviderDisabled(String provider){}
         public void onProviderEnabled(String provider){}
         public void onStatusChanged(String provider, int status, Bundle extras){}
    }; 

    /**
     * Network location listener.
     */
    public final LocationListener networkLocationListener = new LocationListener(){
        @Override
         public void onLocationChanged(Location location){
        
        }
         public void onProviderDisabled(String provider){}
         public void onProviderEnabled(String provider){}
         public void onStatusChanged(String provider, int status, Bundle extras){}
    }; 


    /**
     * Returns best location using LocationManager.getBestProvider()
     * 
     * @param context
     * @return Location|null
     */
    public static Location getLocation(Context context){
        System.println("getLocation()");
    
        // fetch last known location and update it
        try {
            LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
             
            Criteria criteria = new Criteria();
            criteria.setAccuracy(Criteria.ACCURACY_FINE);
             criteria.setAltitudeRequired(false);
             criteria.setBearingRequired(false);
             criteria.setCostAllowed(true);
             String strLocationProvider = lm.getBestProvider(criteria, true);
            
             System.println("strLocationProvider=" + strLocationProvider);
             Location location = lm.getLastKnownLocation(strLocationProvider);
             if(location != null){
                return location;
             }
             return null;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

This class tries to connect to min_gps_sat_count satellites if GPS is enabled. Else returns LocationManager.getBestProvider() location. Check the code!

ANSWER:

Here’s what I do:

  1. First of all I check what providers are enabled. Some may be disabled on the device, some may be disabled in application manifest.
  2. If any provider is available I start location listeners and timeout timer. It’s 20 seconds in my example, may not be enough for GPS so you can enlarge it.
  3. If I get update from location listener I use the provided value. I stop listeners and timer.
  4. If I don’t get any updates and timer elapses I have to use last known values.
  5. I grab last known values from available providers and choose the most recent of them.

Here’s how I use my class:

LocationResult locationResult = new LocationResult(){
    @Override
    public void gotLocation(Location location){
        //Got the location!
    }
};
MyLocation myLocation = new MyLocation();
myLocation.getLocation(this, locationResult);

And here’s MyLocation class:

import java.util.Timer;
import java.util.TimerTask;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

public class MyLocation {
    Timer timer1;
    LocationManager lm;
    LocationResult locationResult;
    boolean gps_enabled=false;
    boolean network_enabled=false;

    public boolean getLocation(Context context, LocationResult result)
    {
        //I use LocationResult callback class to pass location value from MyLocation to user code.
        locationResult=result;
        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)
            return false;

        if(gps_enabled)
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
        if(network_enabled)
            lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
        timer1=new Timer();
        timer1.schedule(new GetLastLocation(), 20000);
        return true;
    }

    LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            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) {
            timer1.cancel();
            locationResult.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())
                     locationResult.gotLocation(gps_loc);
                 else
                     locationResult.gotLocation(net_loc);
                 return;
             }

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

    public static abstract class LocationResult{
        public abstract void gotLocation(Location location);
    }
}

Somebody may also want to modify my logic. For example if you get update from Network provider don’t stop listeners but continue waiting. GPS gives more accurate data so it’s worth waiting for it. If timer elapses and you’ve got update from Network but not from GPS then you can use value provided from Network.

One more approach is to use LocationClient http://developer.android.com/training/location/retrieve-current.html. But it requires Google Play Services apk to be installed on user device.

ANSWER:

I have created small application with step by step description to gets current locations GPS co-ordinates.

enter image description here

Complete example source code in below URL:


Get Current Location coordinates , City name – in Android


See How it works :

  • All we need to do is add this permission in manifest file

    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION">  
    </uses-permission>
    
  • and create LocationManager instance like this

    LocationManager locationManager = (LocationManager) 
                                      getSystemService(Context.LOCATION_SERVICE);
    
  • Check GPS is enabled or not

  • then implement LocationListener and Get Coordinates

    LocationListener locationListener = new MyLocationListener();  
    locationManager.requestLocationUpdates(  
    LocationManager.GPS_PROVIDER, 5000, 10, locationListener);
    
  • here is the sample code to do


/*----------Listener class to get coordinates ------------- */
private class MyLocationListener implements LocationListener {

    @Override
    public void onLocationChanged(Location loc) {
        editLocation.setText("");
        pb.setVisibility(View.INVISIBLE);
        Toast.makeText(
            getBaseContext(),
            "Location changed: Lat: " + loc.getLatitude() + " Lng: "
                + loc.getLongitude(), Toast.LENGTH_SHORT).show();
        String longitude = "Longitude: " + loc.getLongitude();
        Log.v(TAG, longitude);
        String latitude = "Latitude: " + loc.getLatitude();
        Log.v(TAG, latitude);
        /*-------to get City-Name from coordinates -------- */
        String cityName = null;
        Geocoder gcd = new Geocoder(getBaseContext(), Locale.getDefault());
        List<Address> addresses;
        try {
            addresses = gcd.getFromLocation(loc.getLatitude(),
                loc.getLongitude(), 1);
            if (addresses.size() > 0)
                System.out.println(addresses.get(0).getLocality());
            cityName = addresses.get(0).getLocality();
        } catch (IOException e) {
            e.printStackTrace();
        }
        String s = longitude + "\n" + latitude + "\n\nMy Current City is: "
            + cityName;
        editLocation.setText(s);
    }

    @Override
    public void onProviderDisabled(String provider) {}

    @Override
    public void onProviderEnabled(String provider) {}

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {}
}

ANSWER:

With Fedor’s solution I’ve experienced multiple execution of the callback gotLocation.
It seems to be due to a race condition in the overridden LocationListener.onLocationChanged method, when gotLocation method is ‘long enough’. I’m not sure, but I guess removeUpdates prevents the enqueueing of new messages in the Looper queue, but it doesn’t remove those already enqueued but not yet consumed. Hence the race condition.

To reduce the probability of this wrong behavior it’s possible to call removeUpdates before firing the onLocationChanged event, but still we have the race condition.

The best solution I found is to replace requestLocationUpdates with requestSingleUpdate.

This is my version, based on Fedor’s solution, using an Handler to send a message to the looper thread:

public class LocationResolver {
    private Timer timer;
    private LocationManager locationManager;
    private LocationResult locationResult;
    private boolean gpsEnabled = false;
    private boolean networkEnabled = false;
    private Handler locationTimeoutHandler;

    private final Callback locationTimeoutCallback = new Callback() {
        public boolean handleMessage(Message msg) {
            locationTimeoutFunc();
            return true;
        }

        private void locationTimeoutFunc() {   
            locationManager.removeUpdates(locationListenerGps);
            locationManager.removeUpdates(locationListenerNetwork);

            Location networkLocation = null, gpsLocation = null;
            if (gpsEnabled)
                gpsLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            if (networkEnabled)
                networkLocation = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

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

            if (gpsLocation != null) {
                locationResult.gotLocation(gpsLocation);
                return;
            }
            if (networkLocation != null) {
                locationResult.gotLocation(networkLocation);
                return;
            }
            locationResult.gotLocation(null);           
        }
    };
    private final LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {              
            timer.cancel();
            locationResult.gotLocation(location);
            locationManager.removeUpdates(this);
            locationManager.removeUpdates(locationListenerNetwork);
        }

        public void onProviderDisabled(String provider) {
        }

        public void onProviderEnabled(String provider) {
        }

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

        public void onProviderDisabled(String provider) {
        }

        public void onProviderEnabled(String provider) {
        }

        public void onStatusChanged(String provider, int status, Bundle extras) {
        }
    };

    public void prepare() {
        locationTimeoutHandler = new Handler(locationTimeoutCallback);
    }

    public synchronized boolean getLocation(Context context, LocationResult result, int maxMillisToWait) {
        locationResult = result;
        if (locationManager == null)
            locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);

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

        // don't start listeners if no provider is enabled
        if (!gpsEnabled && !networkEnabled)
            return false;

        if (gpsEnabled)
            locationManager.requestSingleUpdate(LocationManager.GPS_PROVIDER, locationListenerGps, Looper.myLooper());
            //locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
        if (networkEnabled)
            locationManager.requestSingleUpdate(LocationManager.NETWORK_PROVIDER, locationListenerNetwork, Looper.myLooper());
            //locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);

        timer = new Timer();
        timer.schedule(new GetLastLocationTask(), maxMillisToWait);
        return true;
    }

    private class GetLastLocationTask extends TimerTask {
        @Override
        public void run() { 
            locationTimeoutHandler.sendEmptyMessage(0);
        }
    }

    public static abstract class LocationResult {
        public abstract void gotLocation(Location location);
    }
}

I use this class from a customized looper thread, like the following one:

public class LocationGetter {
    private final Context context;
    private Location location = null;
    private final Object gotLocationLock = new Object();
    private final LocationResult locationResult = new LocationResult() {            
        @Override
        public void gotLocation(Location location) {
            synchronized (gotLocationLock) {
                LocationGetter.this.location = location;
                gotLocationLock.notifyAll();
                Looper.myLooper().quit();
            }
        }
    };

    public LocationGetter(Context context) {
        if (context == null)
            throw new IllegalArgumentException("context == null");

        this.context = context;
    }

    public synchronized Coordinates getLocation(int maxWaitingTime, int updateTimeout) {
        try {
            final int updateTimeoutPar = updateTimeout;
            synchronized (gotLocationLock) {            
                new Thread() {
                    public void run() {
                        Looper.prepare();
                        LocationResolver locationResolver = new LocationResolver();
                        locationResolver.prepare();
                        locationResolver.getLocation(context, locationResult, updateTimeoutPar);
                        Looper.loop();
                    }
                }.start();

                gotLocationLock.wait(maxWaitingTime);
            }
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }

        if (location != null)
            coordinates = new Coordinates(location.getLatitude(), location.getLongitude());
        else
            coordinates = Coordinates.UNDEFINED;
        return coordinates; 
    }
}

where Coordinates is a simple class with two properties: latitude and longitude.