Android app that shows path between points along with current location

Question

I'm trying to create an Android application that takes in an origin and destination and works along the lines of a GPS.

I was wondering if it was possible (through Google APIs) to display a map that shows the path between point A and B but also shows your current location on top of that path using GPS. I have seen tutorials and articles on how to display just the path between two points using Google directions and maps API but not combining that with your current location dot.

I have not really started this project yet because I am trying to figure out how to best approach this. Any help, tutorials, examples, suggestions will be appreciated!

Raghunandan · Answer 1 · 2013-05-17T18:02:09.130

You must get the your current latitude and longitude first. You can check the link for the same in the below link

http://developer.android.com/guide/topics/location/strategies.html

You must fetch the latitude and longitudes between source and destination. Which should be done using asynctask.

new connectAsyncTask().execute()

The asynctask class

 private class connectAsyncTask extends AsyncTask<Void, Void, Void>{
     private ProgressDialog progressDialog;
     @Override
     protected void onPreExecute() {
         // TODO Auto-generated method stub
         super.onPreExecute();
         progressDialog = new ProgressDialog(MainActivity.this);
         progressDialog.setMessage("Fetching route, Please wait...");
         progressDialog.setIndeterminate(true);
         progressDialog.show();
     }
     @Override
     protected Void doInBackground(Void... params) {
         // TODO Auto-generated method stub
         fetchData();
         return null;
     }
     @Override
     protected void onPostExecute(Void result) {
         super.onPostExecute(result);           
         if(doc!=null){
             NodeList _nodelist = doc.getElementsByTagName("status");
             Node node1 = _nodelist.item(0);
             String _status1  = node1.getChildNodes().item(0).getNodeValue();
             if(_status1.equalsIgnoreCase("OK")){
              Toast.makeText(MainActivity.this,"OK" , 1000).show();
                 NodeList _nodelist_path = doc.getElementsByTagName("overview_polyline");
                 Node node_path = _nodelist_path.item(0);
                 Element _status_path = (Element)node_path;
                 NodeList _nodelist_destination_path = _status_path.getElementsByTagName("points");
                 Node _nodelist_dest = _nodelist_destination_path.item(0);
                 String _path  = _nodelist_dest.getChildNodes().item(0).getNodeValue();
                 List<LatLng> points = decodePoly(_path);
                 for (int i = 0; i < points.size() - 1; i++) {
                   LatLng src = points.get(i);
                   LatLng dest = points.get(i + 1);
                    // Polyline to display the routes
                   Polyline line = mMap.addPolyline(new PolylineOptions()
                           .add(new LatLng(src.latitude, src.longitude),
                            new LatLng(dest.latitude,dest.longitude))
                           .width(2).color(Color.BLUE).geodesic(true))   
               }
                 progressDialog.dismiss();
             }else{
                               // Unable to find route
                  }
         }else{
                         // Unable to find route
         }
     }
 }

DecodePoly function

   private List<LatLng> decodePoly(String encoded) {    
        List<LatLng> poly = new ArrayList<LatLng>();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;
        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;
            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;
            LatLng p = new LatLng((((double) lat / 1E5)), (((double) lng / 1E5)));
            poly.add(p);
        }
        return poly;
    }

Fetch data

Here flati and flongi is the source latitude and longitude

dlati and dlongi is the destination latitude and longitude

 Document doc = null;
 private void fetchData()
 {
     StringBuilder urlString = new StringBuilder();
     urlString.append("http://maps.google.com/maps/api/directions/xml?origin=");
     urlString.append( Double.toString(flati));
     urlString.append(",");
     urlString.append( Double.toString(flongi));
     urlString.append("&destination=");//to
     urlString.append( Double.toString(dlati));
     urlString.append(",");
     urlString.append( Double.toString(dlongi));
     urlString.append("&sensor=true&mode=walking");    
     Log.d("url","::"+urlString.toString());
     HttpURLConnection urlConnection= null;
     URL url = null;
     try
     {
         url = new URL(urlString.toString());
         urlConnection=(HttpURLConnection)url.openConnection();
         urlConnection.setRequestMethod("GET");
         urlConnection.setDoOutput(true);
         urlConnection.setDoInput(true);
         urlConnection.connect();
         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder db = dbf.newDocumentBuilder();
         doc = (Document) db.parse(urlConnection.getInputStream());//Util.XMLfromString(response);
     }catch (MalformedURLException e){
         e.printStackTrace();
     }catch (IOException e){
         e.printStackTrace();
     }catch (ParserConfigurationException e){
         e.printStackTrace();
     }
     catch (SAXException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }
 }

enter image description here

@Zack i cannot chat. I have been blocked by SO. However you could ask Emil Adz. I can only comment for another 7 days — Raghunandan, May 17 '13 at 18:10
@Zack for more details you can check the tutorial here http://raghunandankavi.blogspot.in/. However it might not look good — Raghunandan, May 17 '13 at 18:25

score 0 · Answer 2 · edited May 23 '17 at 11:43

0

You can get an idea on how to implement Google Map API V2 in your application by reading this guide I wrote on this topic:

Google Map API V2

Then you could implement the driving navigation root using this answer I gave here:

Draw driving route between 2 GeoPoints on GoogleMap SupportMapFragment

and to find your current location you should implement a loicationListener, you can see an example here:

http://about-android.blogspot.co.il/2010/04/find-current-location-in-android-gps.html

edited May 23 '17 at 11:43

Community

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answered May 17 '13 at 17:51

Emil Adz

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din't you have this in your blog. – Raghunandan May 17 '13 at 18:07
@Raghunandan, have what in my blog? – Emil Adz May 17 '13 at 18:17
the tutorial regarding displaying routes between two points on the map. i also made a blog but it does not look good. yours looks nice. especially the black background. which blog are you using? – Raghunandan May 17 '13 at 18:19
It's Wordpress, and some free theme I picked up from their collection. If it's interests I could check which one is it. Regarding you question, No I hadn't had time to write on this topic yet. It's in my plans but had not done it yet. – Emil Adz May 17 '13 at 18:22
i wrote this blog http://raghunandankavi.blogspot.in/ looks horible, i used google's blogger. You can let me know of the theme – Raghunandan May 17 '13 at 18:24
the theme called: Dark Temptation, I don't know if it's exists in google's blogger. I think that the blog doesn't look so bad, your problem is that your are not using some kind of syntax editor, like I use: "SyntaxHighlighter Evolved", when you adding code to your post. – Emil Adz May 17 '13 at 18:29
Thanks will look into it and creative blog – Raghunandan May 17 '13 at 18:29

Android app that shows path between points along with current location

2 Answers2