Google Maps Utils how to decode polylines values from list?

Question

I'm using Google Maps Directions Api and the Google Maps Utils library to draw a path between my location to a marker, I was retrieving the field overview-polyline from the Directions Api, but the polyline that was drawn was not right so now I'm trying to build the polyline step by step, but I'm facing a problem, I was able to add to a arraylist all the polylines but now how do I retrieve them from the arraylist to decoded and build them;

This is the JSON:

{
geocoded_waypoints: [
{},
{}
],
routes: [
{
bounds: {},
copyrights: "Dados do mapa ©2017 Google, Inst. Geogr. Nacional",
legs: [
{
distance: {},
duration: {},
end_address: "14 Avenue Latécoère, 31700 Cornebarrieu, França",
end_location: {},
start_address: "R. Zeferino Brandão 9, 2005 Santarém, Portugal",
start_location: {},
steps: [
{
distance: {},
duration: {},
end_location: {},
html_instructions: "Siga para <b>noroeste</b> na <b>R. Zeferino Brandão</b> em direção a <b>Tv. de São Domingos</b>",
polyline: {
points: "k|nnF`p_t@GB{@t@MFQPMLKXETEZCVCL?@?BAD?@?DAFC|@"
},
start_location: {},
travel_mode: "DRIVING"
},
{},

This is how I decoded the overview-polyline:

...
JSONObject singleRout = (JSONObject) routes.get(0);
    JSONObject overview_polyline = (JSONObject) singleRout.get("overview_polyline");
        if (overview_polyline != null) {
            points = overview_polyline.getString("points");
        }
...

protected void fazerCaminho() {
    List<LatLng> decodedPath = PolyUtil.decode(points);

    if (line == null) {
        line = mMap.addPolyline(new PolylineOptions()
                .width(3)
                .color(Color.rgb(25, 151, 152))
                .geodesic(true)
                .addAll(decodedPath));
    } else {
        line.remove();
        line = mMap.addPolyline(new PolylineOptions()
                .width(3)
                .color(Color.rgb(25, 151, 152))
                .geodesic(true)
                .addAll(decodedPath));
    }
}

Now I'm adding all the points to the arraylist like this:

JSONObject singlePolyline = (JSONObject) singleStep.get("polyline");
    if (singlePolyline != null) {
        points = singlePolyline.getString("points");
        caminho.put("points" , points);
    }

    listaPolylines.add(caminho);

How do I decode now the values from the list?

Answer 1

You can use the PolyUtil.decode method from the Google Maps Android API Utility Library:

List<LatLng> decoded = PolyUtil.decode(caminho.get("points"));

In your case, if you want to decode from your listaPolylines:

for (Map polyline : listaPolylines) {
    List<LatLng> decoded = PolyUtil.decode(polyline.get("points"));

    // Do something with your decoded polyline. For example drawing it on your map
    mMap.addPolyline(new PolylineOptions().addAll(decoded));
}