@Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        dialogo.dismiss();

        lista.setAdapter(new MiListaAdapter(cxt, R.layout.item_list, jsonArray, lat1, lon1));
        lista.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    }

public static double distance(LatLng StartP, LatLng EndP) {
    double lat1 = StartP.latitude;
    double lat2 = EndP.latitude;
    double lon1 = StartP.longitude;
    double lon2 = EndP.longitude;
    double dLat = Math.toRadians(lat2-lat1);
    double dLon = Math.toRadians(lon2-lon1);
    double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
            Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
                    Math.sin(dLon/2) * Math.sin(dLon/2);
    double c = 2 * Math.asin(Math.sqrt(a));
    return 6366000 * c;
}

Double distance = distance(new LatLng(lat1, lon1),
                new LatLng(Double.parseDouble(lat2), Double.parseDouble(lon2)));

        v.txtDistancia.setText("Distancia: " + distance);