Good Way of Getting the User's Location in Android

Good way of getting the user's location in Android

Looks like we're coding the same application ;-)

Here is my current implementation. I'm still in the beta testing phase of my GPS uploader app, so there might be many possible improvements. but it seems to work pretty well so far.

/**
 * try to get the 'best' location selected from all providers
 */
private Location getBestLocation() {
    Location gpslocation = getLocationByProvider(LocationManager.GPS_PROVIDER);
    Location networkLocation =
            getLocationByProvider(LocationManager.NETWORK_PROVIDER);
    // if we have only one location available, the choice is easy
    if (gpslocation == null) {
        Log.d(TAG, "No GPS Location available.");
        return networkLocation;
    }
    if (networkLocation == null) {
        Log.d(TAG, "No Network Location available");
        return gpslocation;
    }
    // a locationupdate is considered 'old' if its older than the configured
    // update interval. this means, we didn't get a
    // update from this provider since the last check
    long old = System.currentTimeMillis() - getGPSCheckMilliSecsFromPrefs();
    boolean gpsIsOld = (gpslocation.getTime() < old);
    boolean networkIsOld = (networkLocation.getTime() < old);
    // gps is current and available, gps is better than network
    if (!gpsIsOld) {
        Log.d(TAG, "Returning current GPS Location");
        return gpslocation;
    }
    // gps is old, we can't trust it. use network location
    if (!networkIsOld) {
        Log.d(TAG, "GPS is old, Network is current, returning network");
        return networkLocation;
    }
    // both are old return the newer of those two
    if (gpslocation.getTime() > networkLocation.getTime()) {
        Log.d(TAG, "Both are old, returning gps(newer)");
        return gpslocation;
    } else {
        Log.d(TAG, "Both are old, returning network(newer)");
        return networkLocation;
    }
}

/**
 * get the last known location from a specific provider (network/gps)
 */
private Location getLocationByProvider(String provider) {
    Location location = null;
    if (!isProviderSupported(provider)) {
        return null;
    }
    LocationManager locationManager = (LocationManager) getApplicationContext()
            .getSystemService(Context.LOCATION_SERVICE);
    try {
        if (locationManager.isProviderEnabled(provider)) {
            location = locationManager.getLastKnownLocation(provider);
        }
    } catch (IllegalArgumentException e) {
        Log.d(TAG, "Cannot acces Provider " + provider);
    }
    return location;
}

Edit: here is the part that requests the periodic updates from the location providers:

public void startRecording() {
    gpsTimer.cancel();
    gpsTimer = new Timer();
    long checkInterval = getGPSCheckMilliSecsFromPrefs();
    long minDistance = getMinDistanceFromPrefs();
    // receive updates
    LocationManager locationManager = (LocationManager) getApplicationContext()
            .getSystemService(Context.LOCATION_SERVICE);
    for (String s : locationManager.getAllProviders()) {
        locationManager.requestLocationUpdates(s, checkInterval,
                minDistance, new LocationListener() {

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

                    @Override
                    public void onProviderEnabled(String provider) {}

                    @Override
                    public void onProviderDisabled(String provider) {}

                    @Override
                    public void onLocationChanged(Location location) {
                        // if this is a gps location, we can use it
                        if (location.getProvider().equals(
                                LocationManager.GPS_PROVIDER)) {
                            doLocationUpdate(location, true);
                        }
                    }
                });
        // //Toast.makeText(this, "GPS Service STARTED",
        // Toast.LENGTH_LONG).show();
        gps_recorder_running = true;
    }
    // start the gps receiver thread
    gpsTimer.scheduleAtFixedRate(new TimerTask() {

        @Override
        public void run() {
            Location location = getBestLocation();
            doLocationUpdate(location, false);
        }
    }, 0, checkInterval);
}

public void doLocationUpdate(Location l, boolean force) {
    long minDistance = getMinDistanceFromPrefs();
    Log.d(TAG, "update received:" + l);
    if (l == null) {
        Log.d(TAG, "Empty location");
        if (force)
            Toast.makeText(this, "Current location not available",
                    Toast.LENGTH_SHORT).show();
        return;
    }
    if (lastLocation != null) {
        float distance = l.distanceTo(lastLocation);
        Log.d(TAG, "Distance to last: " + distance);
        if (l.distanceTo(lastLocation) < minDistance && !force) {
            Log.d(TAG, "Position didn't change");
            return;
        }
        if (l.getAccuracy() >= lastLocation.getAccuracy()
                && l.distanceTo(lastLocation) < l.getAccuracy() && !force) {
            Log.d(TAG,
                    "Accuracy got worse and we are still "
                      + "within the accuracy range.. Not updating");
            return;
        }
        if (l.getTime() <= lastprovidertimestamp && !force) {
            Log.d(TAG, "Timestamp not never than last");
            return;
        }
    }
    // upload/store your location here
}

Things to consider:

• do not request GPS updates too often, it drains battery power. I currently
  use 30 min as default for my application.

• add a 'minimum distance to last known location' check. without this, your points
  will "jump around" when GPS is not available and the location is being triangulated
  from the cell towers. or you can check if the new location is outside of the accuracy
  value from the last known location.

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

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.

What is the simplest and the best way to get the user's current location on Android?

To get the latest location call this in your oncreate view

 fusedLocationClient = LocationServices.getFusedLocationProviderClient(this);

then use the following code to get location

fusedLocationClient.getLastLocation()
    .addOnSuccessListener(this, new OnSuccessListener<Location>() {
        @Override
        public void onSuccess(Location location) {
            // Got last known location. In some rare situations this can be null.
            if (location != null) {
                // Logic to handle location object
            }
        }
    });

This works by giving you the latest know location

Get user location at high speed

My solution was to calculate the missing location between pointA and pointB, knowing that the maximum rate at what the GPS gives updates is 1s. In real life situations I had to deduct 3 to 4 points when people drive in highways at high speed.

private fun processMissingPoints() {
    val stepInMeters = lastUsedLocation.distanceTo(lastKnownLocation) / (numberOfMissingPoints).toDouble()
    val bearing = lastUsedLocation.bearingTo(lastKnownLocation)
    missingPoints.forEach{ point ->
        val newCoordinates = getNewCoordinates(lastUsedLocation.latitude , lastUsedLocation.longitude,stepInMeters*(index+1), bearing.toDouble())
    }
}


/**
 * http://www.movable-type.co.uk/scripts/latlong.html#dest-point
 * Given a start point, initial bearing, and distance, this will calculate the destination
 * point and final bearing travelling along a (shortest distance) great circle arc.
 */
private fun getNewCoordinates(latitude: Double,longitude: Double,distanceInMetres: Double,bearing: Double) : LatLng{
    val brngRad = toRadians(bearing)
    val latRad = toRadians(latitude)
    val lonRad = toRadians(longitude)
    val earthRadiusInMetres = 6371000
    val distFrac = distanceInMetres / earthRadiusInMetres

    val latitudeResult = asin(sin(latRad) * cos(distFrac) + cos(latRad) * sin(distFrac) * cos(brngRad))
    val a = atan2(sin(brngRad) * sin(distFrac) * cos(latRad), cos(distFrac) - sin(latRad) * sin(latitudeResult))
    val longitudeResult = (lonRad + a + 3 * PI) % (2 * PI) - PI

    return LatLng(toDegrees(latitudeResult),toDegrees(longitudeResult))
}

Getting user's location Android

My suggestion is first one. com.google.android.gms.location.LocationListener abstracts fiding location from your code.
For sample code look at here please. It works fine for me with cell network or wifi.

Getting locations near User's Location

private static double distanceInKm(double lat1, double lon1, double lat2, double lon2) {
        int R = 6371; // km
        double x = (lon2 - lon1) * Math.cos((lat1 + lat2) / 2);
        double y = (lat2 - lat1);
        return (Math.sqrt(x * x + y * y) * R) / 1000;
    }

Or

Location location1 = new Location("");
location1.setLatitude(latitude1);
location1.setLongitude(longitude1);

Location location2 = new Location("");
location2.setLatitude(latitude2);
location2.setLongitude(longitude2);

float distanceInKm = (location1.distanceTo(location2))/1000;

Get current location during app launch

Use this technique :

LocationManager locManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

boolean network_enabled = locManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

Location location;

if(network_enabled){

   location = locManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

if(location!=null){
   longitude = location.getLongitude();
   latitude = location.getLatitude();
    }                
}

In this case you even no need to on GPS only your mobile network will do.

Don't forget to give the following permission in Manifest:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

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