Question

I need to draw a path on the map. To do so, i thought about using Polyline since the new google maps. My problem is that my application works, but it doesnt draw a thing on the map. I want it to draw everytime i change position, basically to draw my path.

public class MapActivity extends FragmentActivity implements LocationListener {
    GoogleMap               myMap;
    Location                lastLocation;
    private LocationManager locManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.map_layout);
        myMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
        myMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);


        locManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        boolean networkEnabled = locManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        if (!networkEnabled) {
            Toast.makeText(this, "network not enabled", 0);
        }

    }

    @Override
    protected void onResume() {
        super.onResume();
        locManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, this);

    }


    @Override
    public void onLocationChanged(Location location) {
        if (location != null) {
            lastLocation=locManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            Polyline line=myMap.addPolyline(new PolylineOptions().add(new LatLng(location.getLatitude(),location.getLongitude())).color(Color.RED));

        }
    }

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

    }

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

    }

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

Answer 1

Lines require a minimum of two points. You are attempting to draw a line using only a single point. This will draw an infinitely small line, which you will have difficulty seeing, since it is infinitely small.

If you want to draw a line, use two or more points. If you want to draw something at a single point, use a marker, not a polyline.