Google Maps：为什么折线是从（0,0）而不是从Android的起点绘制的

Question

The starting point of my poly-line is starting from lat 0, long 0. I don't know why because i want it to start from the start point which in my case is the current location i am to a destination point specified. The polyline does not clear after the draw when it draws to another point. here is the code for polylines:

protected void onPostExecute(List<List<HashMap<String, String>>> result) {
        ArrayList<LatLng> points = null;
        double lat = 0;
        double lng = 0;
          PolylineOptions lineOptions = null;
        // Toast.makeText(getApplicationContext(), ""+result,
        // Toast.LENGTH_LONG).show();
        // Traversing through all the routes
        String dat = "";String dat1 = "";
        for (int i = 0; i < result.size(); i++) {
            points = new ArrayList<LatLng>();
            lineOptions = new PolylineOptions();

            // Fetching i-th route
            List<HashMap<String, String>> path = result.get(i);
            // Toast.makeText(getApplicationContext(), point.get("lat"),
            // Toast.LENGTH_LONG).show();
            // Fetching all the points in i-th route


            for (int j = 1; j < path.size(); j++) {
                HashMap<String, String> point  = path.get(j);
                dat = point.get("lat");dat1 = point.get("lng");
                if (dat != null&&dat!="0.0"&&dat1 != null&&dat1!="0.0") {
                    lat = Double.parseDouble(point.get("lat"));
                    lng = Double.parseDouble(point.get("lng"));
            }
                // lat=Float.parseFloat(point.get("lat"));
                // lng=Float.parseFloat(point.get("lng"));
 //                  Toast.makeText(getApplicationContext(), "SASA"+lat,
//                   Toast.LENGTH_LONG).show();
//                   lat = Double.parseDouble(point.get("lat"));
//                   lng = Double.parseDouble(point.get("lng"));
                LatLng position = new LatLng(lat, lng);

                points.add(position);
            }

            // Adding all the points in the route to LineOptions
            lineOptions.addAll(points);
            lineOptions.width(4);
            lineOptions.color(Color.RED);
        }

        // Drawing polyline in the Google Map for the i-th route
        mGoogleMap.addPolyline(lineOptions);
    }
}