How to draw a real time route in android, using google maps v2 and gps

Question

I'm trying to draw a path on google maps while moving from my location.
For this I have created a google map activity and a gps service running on background but when I try to run the application I can see my location changed but the route is not showing.

public class HomeActivity extends AppCompatActivity
    implements OnMapReadyCallback, NavigationView.OnNavigationItemSelectedListener {
SessionManager session;
private User user;
private ImageView profileImage;
Bitmap bitmap;
TextView user_name, user_email;
ImageView user_picture;
NavigationView navigation_view;
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
//UI elements
private TextView txtDuration;
private TextView txtDistance;
private Button btnStart;
private Button btnStop;
//kep track if the activity started
private boolean isStarted = false;
//location manager
private LocationManager locManager;
//location listener
private LocationListener myLocationListener;
//route object
private Route route = null;
//list of route coordinates
private List<Coordinate> coordinates = null;
//coordinate object
private Coordinate coordinate = null;
//starting point location
private Location startLocation;
//location service
private  Getlocation locationService;
//intent to start location service
private Intent serviceIntent;
//keep track if we are bound to the service
private boolean serviceBound = false;
private final String TAG = "walk";
//minimum time between updates in milliseconds
private static long MIN_TIME = 1000 * 1 * 3; // 3 seconds
//polyline options
private PolylineOptions polylineOptions;
//polyline
private Polyline polyline;
//list of LatLng objects
private List<LatLng> path = new ArrayList<LatLng>();
//broadcast receiver
private BroadcastReceiver receiver;
//average speed
private double avSpeed = 0.0;
//flag for gps enabled status
private boolean isGPSEnabled = false;
//map type
private int MAP_TYPE = GoogleMap.MAP_TYPE_NORMAL;
//route colour
private int ROUTE_COLOUR = Color.BLUE;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setTitle("Run");



    // btnStart = (Button) findViewById(R.id.btn_start);
    Intent intent = getIntent();
    String jsondata = intent.getStringExtra("jsondata");

    setNavigationHeader();    // call setNavigationHeader Method.
    setUserProfile(jsondata);  // call setUserProfile Method.


    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    navigation_view.setNavigationItemSelectedListener(this);


    //get reference to UI elements
    btnStart = (Button) findViewById(R.id.btn_start_activity);
    btnStop = (Button) findViewById(R.id.btn_stop);

    txtDuration = (TextView) findViewById(R.id.txt_duration);
    txtDistance = (TextView) findViewById(R.id.txt_distance);
    //if walking session is not running set duration text to default value
    if (!isStarted)
        txtDuration.setText("00:00:00");
    locManager = (LocationManager) getApplicationContext().getSystemService(LOCATION_SERVICE);
    isGPSEnabled = locManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

    bindToService();
    //set UI elements visibility
    setVisibility();

}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
        moveTaskToBack(true);
    }
}

/*
    Set Navigation header by using Layout Inflater.
 */

public void setNavigationHeader(){

    navigation_view = (NavigationView) findViewById(R.id.nav_view);

    View header = LayoutInflater.from(this).inflate(R.layout.nav_header_home, null);
    navigation_view.addHeaderView(header);

    user_name = (TextView) header.findViewById(R.id.username);
    user_picture = (ImageView) header.findViewById(R.id.profile_pic);
    user_email = (TextView) header.findViewById(R.id.email);
}

/*
   Set User Profile Information in Navigation Bar.
 */

public  void  setUserProfile(String data){
    user = PrefUtils.getCurrentUser(HomeActivity.this);
    session = new SessionManager(getApplicationContext());
    HashMap<String, String> userpm = session.getUserDetailsfb();
    String imgurl = userpm.get(SessionManager.KEY_IMGURL);
    user_email.setText(userpm.get(SessionManager.KEY_EMAIL));
    user_name.setText(userpm.get(SessionManager.KEY_NAME));

    //    new LoadProfileImage(user_picture).execute(imgurl);


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    //   getMenuInflater().inflate(R.menu.home, menu);
    getMenuInflater().inflate(R.menu.menu_session, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_parcours) {

    } else if (id == R.id.nav_historique) {

    } else if (id == R.id.nav_friends) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_logout) {
        PrefUtils.clearCurrentUser(HomeActivity.this);
        // We can logout_layout from facebook by calling following method
        LoginManager.getInstance().logOut();
        Intent i = new Intent(HomeActivity.this, MainActivity.class);
        startActivity(i);
        finish();
    }


    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

/**
 * connect to the service
 */
private ServiceConnection serviceConnection = new ServiceConnection() {

    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        Getlocation.LocationBinder binder = ( Getlocation.LocationBinder) service;
        //get service
        locationService = binder.getService();

        Log.e(TAG, "on service connected, bound is: " + serviceBound + " service: " + locationService + " intent: " + serviceIntent);
    }

    //the following gets called when connection with service gets unexpectidly disconnected
    @Override
    public void onServiceDisconnected(ComponentName name) {
        locationService = null;
        serviceBound = false;

    }
};

/**
 * bind to service to access its public methods
 */
private void bindToService() {
    Log.e(TAG, "binding to service, bound is: " + serviceBound + " service: " + locationService + " intent: " + serviceIntent);
    //if intent is not created
    if (serviceIntent == null) {
        //create intent
        serviceIntent = new Intent(this,  Getlocation.class);
    }
    //start service
    startService(serviceIntent);
    //bind to service
    bindService(serviceIntent, serviceConnection, Context.BIND_AUTO_CREATE);
    serviceBound = true;
    Log.e(TAG, "after, bound is: " + serviceBound + " service: " + locationService + " intent: " + serviceIntent);

}

/**
 * set click listeners for UI elements
 */
private void setListeners() {
    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            //activity started
            isStarted = true;
            //set UI elements visibility
            setVisibility();
            //start tracking
            startTracking();
            //}
        }
    });



    btnStop.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //activity stopped - reset flags
            isStarted = false;
            Log.e(TAG, "stop clicked, started: " + isStarted );
            //set UI elements visibility
            setVisibility();
            //stop tracking
            stopTracking();
            //show history
        }
    });
}

/**
 * set UI elements visibility
 */
private void setVisibility() {
    Log.e(TAG, "set visible, started: " + isStarted );
    //if activity is started
    if (isStarted) {//show activity controls
        findViewById(R.id.activity_controls).setVisibility(View.VISIBLE);
        //hide start activty button
        findViewById(R.id.btn_start_activity).setVisibility(View.INVISIBLE);
        //toggle lock button appearance depending on its status
    } else {//if activity is stopped or the app is just loaded
        //hide activity controls
        findViewById(R.id.activity_controls).setVisibility(View.INVISIBLE);
        //show start activity button
        findViewById(R.id.btn_start_activity).setVisibility(View.VISIBLE);
    }
    setActionBarVisibility();
}
@Override
protected void onResume() {
    super.onResume();
    if (!serviceBound && isStarted)
        bindToService();
    setActionBarVisibility();
    //get location updates from receiver
    receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            //Log.e(TAG,"on recieve");
            Bundle b = intent.getExtras();
            final Location loc = (Location) b.get(android.location.LocationManager.KEY_LOCATION_CHANGED);
            Location loc2 = (Location)b.getParcelable("location");
            //Log.e(TAG, "on recieve, loc:" + loc + " loc2(extra)" + loc2);
            //get corresponding values from service (distance, speed, location)
            final String distance = String.format("%.2f", locationService.getDistance());
            final double distanceKm = Double.parseDouble(distance);
            //if location is not null - add new value to list of LatLng objects
            if (loc != null) {
                path.add(getLatLng(loc));
            }
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    //update route info on display
                    txtDistance.setText(distance);
                    updateCamera(loc);
                    updatePolyline(loc);

                }
            });
        }
    };

    setUpMapIfNeeded();
    setListeners();

    Log.e(TAG, "on resume, bound: " + serviceBound + " started: " + isStarted );
}

@Override
protected void onStart() {
    super.onStart();
    if (!serviceBound && isStarted)
        bindToService();
    //LocalBroadcastManager.getInstance(this).registerReceiver((receiver),
    //      new IntentFilter(LocationService.LOCATION_UPDATE));
    Log.e(TAG, "on start, bound: " + serviceBound);
}

@Override
protected void onStop() {
    Log.e(TAG, "on stop, bound: " + serviceBound);
    if (serviceBound)
        unbindFromService();
    super.onStop();
    Log.e(TAG, "on stop, bound: " + serviceBound);
}



@Override
protected void onDestroy() {
    super.onDestroy();
    Log.e(TAG, "on destroy, bound: " + serviceBound);
}

@Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    Log.e(TAG, "on new intent, bound: " + serviceBound + " intent: " + intent);
    if (!serviceBound)
        bindToService();
    setActionBarVisibility();
}

/**
 * unbind from service
 */
private void unbindFromService() {
    if (serviceBound) {
        unbindService(serviceConnection);
        serviceBound = false;
    }
}

private void setUpMapIfNeeded() {
    Log.e(TAG, "in setup map if needed, map: " + mMap);
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map_view))
                .getMap();
        //Map Settings
        mMap.getUiSettings().setMyLocationButtonEnabled(true);
        mMap.getUiSettings().setCompassEnabled(true);
        mMap.getUiSettings().setZoomControlsEnabled(true);
        //map type
        mMap.setMapType(MAP_TYPE);
        // Check if we were successful in obtaining the map.
        if (mMap != null) {
            mMap.setOnMapLoadedCallback(new GoogleMap.OnMapLoadedCallback() {
                @Override
                public void onMapLoaded() {
                    Log.e(TAG, "map loaded");
                    setUpMap();
                }
            });

        }
    }
}

 // initialise map to reflect current position

private void setUpMap() {
    //initialise polyline options
    polylineOptions = new PolylineOptions();
    //path colour from shared preferences
    polylineOptions.color(ROUTE_COLOUR).width(4);
    //check if GPS is enabled on the device
    if (!isGPSEnabled) {
        //if GPS is off - show warning
        gpsOffAlert();
    } else {//if GPS is on
        //get current location
        Location location = getLastKnownLocation();
        Log.e(TAG, "in setup map, location: " + location);
        //if such location exists/registered - update camera position
        if (location != null) {
            mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(getLatLng(location), 16));

            Log.e(TAG, "in setup map, found last location, location: " + location);
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    ActivityCompat#requestPermissions
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for ActivityCompat#requestPermissions for more details.
                return;
            }
            mMap.setMyLocationEnabled(true);

            //set route start location
            setStartLocation(location);
            //draw initial polyline
            polyline = mMap.addPolyline(polylineOptions.add(getLatLng(location)));
            //add first element to list of LatLng objects
            if (path.size() == 0)
                path.add(getLatLng(location));
        }
    }
    //}

}

/**
 * show alert dialog if gps is off
 */
public void gpsOffAlert() {
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
    // Setting Dialog Title
    alertDialog.setTitle("GPS is off");
    // alert dialog message
    alertDialog.setMessage("GPS is off. This application requires enabled GPS to function. Do you want to go to settings menu and activate GPS?");

    // open settings menu on button press
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            HomeActivity.this.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
            finish();
            //context.startActivity(new Intent(context,MainActivity.class));
        }
    });

    //show alert
    alertDialog.show();
}

/**
 * get last known location querying all available providers
 * @return location
 */
private Location getLastKnownLocation() {
    //locManager = (LocationManager)getApplicationContext().getSystemService(LOCATION_SERVICE);
    List<String> providers = locManager.getProviders(true);
    Location bestLocation = null;
    for (String provider : providers) {

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            Location loc = locManager.getLastKnownLocation(provider);
            return loc;
        }
        Location loc = locManager.getLastKnownLocation(provider);
        Log.e(TAG, "provider found: " + provider + " location: " + loc);
        if (loc == null) {
            continue;
        }
        if (bestLocation == null || loc.getAccuracy() < bestLocation.getAccuracy()) {
            // Found best last known location: %s", l);
            bestLocation = loc;
        }
    }
    return bestLocation;
}

@Override
public void onMapReady(GoogleMap googleMap) {
    Log.e(TAG, "on map ready ");

    mMap = googleMap;

    setUpMap();
}


/**
 * start walking activity tracking
 */
private void startTracking() {
    //ensure we are bound to service
    if (!serviceBound)
        bindToService();
    //get time now
    String routeStartTime = Utils.getCurrentTimeStringShort();
    //instantiate route object
    route = new Route();
    //get today's date in different formats (long, short)
    String routeName = Utils.getFullDateString();
    String routeDate = Utils.getShortDateString();
    //set corresponding route values
    route.setName(routeName);
    route.setDate(routeDate);
    route.setStartTime(routeStartTime);
    //instantiate coordinates list
    coordinates = new ArrayList<Coordinate>();
    //if there is a starting point for the route
    if (getStartLocation() != null) {
        //add that location to list of coordinates
        addPoint(getStartLocation());
    }
    if (coordinates.size() > 0) {
        route.setStartPoint(coordinates.get(0));
    }
    //double check that we are bound to the service
    if (serviceBound) {
        //start tracking
        locationService.startTracking(isStarted);
    }

    //register receiever for location updates
    LocalBroadcastManager.getInstance(this).registerReceiver((receiver),
            new IntentFilter( Getlocation.LOCATION_UPDATE));

}

/**
 * stop tracking
 */
private void stopTracking() {


    //get session duration
    String routeDuration = txtDuration.getText().toString();
    //get finish time
    String routeFinishTime = Utils.getCurrentTimeStringShort();
    //     Log.e(TAG,"stopping session, coordinate size: "+coordinates.size());

    //set route duration and finish time
    route.setFinishTime(routeFinishTime);
    route.setDuration(routeDuration);
    route.setDistance(txtDistance.getText().toString());
    //get reference to db
    RoutesDBHelper.init(HomeActivity.this);
    //insert route object to db
    long routeId = RoutesDBHelper.createRoute(route);
    Log.e(TAG, "route id: " + routeId);
    //read list of coordinates for the route
    coordinates = locationService.getCoordinates();
    //if we have at least two coordinates for the route
    if (coordinates.size() > 1) {
        //set start and finish point from coordinates list
        route.setFinishPoint(coordinates.get(coordinates.size() - 1));
        route.setStartPoint(coordinates.get(0));
    }//if there is only one coordinate for the route
    else if (coordinates.size() == 1) {
        //set start and finish points
        route.setFinishPoint(coordinates.get(0));
        route.setStartPoint(coordinates.get(0));
    }
    //insert list of coordinates to db
    RoutesDBHelper.createCoordinates(coordinates, routeId);
    //}
    //stop tracking
    locationService.stopTracking(isStarted);
    //Log.e(TAG, "route: " + route);
    //Log.e(TAG,"coordinates: "+coordinates);
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        // TODO: Consider calling
        //    ActivityCompat#requestPermissions
        // here to request the missing permissions, and then overriding
        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
        //                                          int[] grantResults)
        // to handle the case where the user grants the permission. See the documentation
        // for ActivityCompat#requestPermissions for more details.
        return;
    }
    mMap.setMyLocationEnabled(false);
    //if bound to service
    if(serviceBound){
        //stop service and unbind
        stopService(serviceIntent);
        unbindService(serviceConnection);
        serviceBound = false;
    }
    //unregister receiever
    LocalBroadcastManager.getInstance(this).unregisterReceiver(receiver);


}

public Location getStartLocation() {
    return startLocation;
}

public void setStartLocation(Location startLocation) {
    this.startLocation = startLocation;
}

private void addPoint(Location location){
    //provided location is not null
    if(location!=null) {
        //add new coordinate to the list of coordinates
        Coordinate point = new Coordinate(location.getLatitude(), location.getLongitude(), location.getAltitude(), location.getSpeed());
        coordinates.add(point);
    }
}

private void updatePolyline(Location location){
    polyline.setPoints(path);
    Log.e(TAG, "setting points with loc: " + path);
}

private void updateCamera(Location location){
    Log.e(TAG, "updating camera with loc: " + location);
    LatLngBounds.Builder builder = new LatLngBounds.Builder();
    //include route points to the boundary builder
    for (LatLng latLng : path) {
        builder.include(latLng);
    }
    mMap.animateCamera(CameraUpdateFactory.newLatLngBounds(builder.build(), 30));
}

private LatLng getLatLng(Location location){
    return new LatLng(location.getLatitude(), location.getLongitude());

}
public Coordinate getStartPoint(){
    return new Coordinate(getStartLocation().getLatitude(),getStartLocation().getLongitude());

}

private void setActionBarVisibility(){
    if(isStarted)
        getSupportActionBar().hide();
    else
        getSupportActionBar().show();
}

Answer 1

This is what I do and it works for me: I create a Google Api Client and implement LocationListener

public class MapsActivity extends FragmentActivity implements
        OnMapReadyCallback,
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        com.google.android.gms.location.LocationListener {


    private GoogleMap map; 
    private Polyline gpsTrack; 
    private SupportMapFragment mapFragment; 
    private GoogleApiClient googleApiClient;
    private LatLng lastKnownLatLng;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);

        mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        if (googleApiClient == null) {
            googleApiClient = new GoogleApiClient.Builder(this)
                    .addConnectionCallbacks(this)
                    .addOnConnectionFailedListener(this)
                    .addApi(LocationServices.API)
                    .build();
        }

    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        map = googleMap;

        LatLng calymayor = new LatLng(19.345822, -99.152274);
        map.moveCamera(CameraUpdateFactory.newLatLng(calymayor));
        map.moveCamera(CameraUpdateFactory.newLatLngZoom(calymayor, 15));

        PolylineOptions polylineOptions = new PolylineOptions();
        polylineOptions.color(Color.CYAN);
        polylineOptions.width(4);
        gpsTrack = map.addPolyline(polylineOptions);

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        map.setMyLocationEnabled(true);

    }


    @Override
    protected void onStart() {
        googleApiClient.connect();
        super.onStart();
    }

    @Override
    protected void onStop() {
        googleApiClient.disconnect();
        super.onStop();
    }

    @Override
    protected void onPause() {
        super.onPause();
        stopLocationUpdates();
    }

    @Override
    public void onResume() {
        super.onResume();
        if (googleApiClient.isConnected()) {
            startLocationUpdates();
        }
    }

    @Override
    public void onConnected(@Nullable Bundle bundle) {
        startLocationUpdates();
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

    }

    @Override
    public void onLocationChanged(Location location) {
        lastKnownLatLng = new LatLng(location.getLatitude(), location.getLongitude());
        updateTrack();
    }

    protected void startLocationUpdates() {
        LocationRequest locationRequest = new LocationRequest();
        locationRequest.setInterval(5000);
        locationRequest.setFastestInterval(1000);
        locationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        LocationServices.FusedLocationApi.requestLocationUpdates(googleApiClient, locationRequest, this);
    }

    protected void stopLocationUpdates() {
        LocationServices.FusedLocationApi.removeLocationUpdates(
                googleApiClient, this);
    }

    private void updateTrack() {
        List<LatLng> points = gpsTrack.getPoints();
        points.add(lastKnownLatLng);
        gpsTrack.setPoints(points);
    }

}

Every time a new Location is detected, I add the latest LatLng point to my Polyline.