Finding road distance between two coordinates in g

Question

I am using the following piece of code to find the road distance between two sets of coordinates in android:

public String getDistance(double lat1, double lon1, double lat2, double lon2) {
        String result_in_kms = "";
        String url = "http://maps.google.com/maps/api/directions/xml?origin=" + lat1 + "," + lon1 + "&destination=" + lat2 + "," + lon2 + "&sensor=false&units=metric";
        String tag[] = {"text"};
        HttpResponse response = null;
        try {
            HttpClient httpClient = new DefaultHttpClient();
            HttpContext localContext = new BasicHttpContext();
            HttpPost httpPost = new HttpPost(url);
            response = httpClient.execute(httpPost, localContext);
            InputStream is = response.getEntity().getContent();
            DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            org.w3c.dom.Document doc = builder.parse(is);
            if (doc != null) {
                NodeList nl;
                ArrayList args = new ArrayList();
                for (String s : tag) {
                    nl = doc.getElementsByTagName(s);
                    if (nl.getLength() > 0) {
                        Node node = nl.item(nl.getLength() - 1);
                        args.add(node.getTextContent());
                    } else {
                        args.add(" - ");
                    }
                }
                result_in_kms =String.valueOf( args.get(0));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        //Float f=Float.valueOf(result_in_kms);
        return result_in_kms;
    }

But instead of the distance between them all i get is a '-'.What is wrong in the above code , i got it from this post:

How to find distance (by road) between 2 geo points in Android application without using google map direction api?

Answer 1

Please try working code as written below:

public String getDistance(final double lat1, final double lon1, final double lat2, final double lon2){

        Thread thread=new Thread(new Runnable() {
            @Override
            public void run() {
                try {

                    URL url = new URL("http://maps.googleapis.com/maps/api/directions/json?origin=" + lat1 + "," + lon1 + "&destination=" + lat2 + "," + lon2 + "&sensor=false&units=metric&mode=driving");
                    final HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.setRequestMethod("POST");
                    InputStream in = new BufferedInputStream(conn.getInputStream());
                    response = iStreamToString(in);

                    JSONObject jsonObject = new JSONObject(response);
                    JSONArray array = jsonObject.getJSONArray("routes");
                    JSONObject routes = array.getJSONObject(0);
                    JSONArray legs = routes.getJSONArray("legs");
                    JSONObject steps = legs.getJSONObject(0);
                    JSONObject distance = steps.getJSONObject("distance");
                    parsedDistance=distance.getString("text");

                    Log.v("Distsnce","Distance>>"+parsedDistance);

                } catch (ProtocolException e) {
                    e.printStackTrace();
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        });
        thread.start();
        try {
            thread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return parsedDistance;
    }


  public String iStreamToString(InputStream is1)
    {
        BufferedReader rd = new BufferedReader(new InputStreamReader(is1), 4096);
        String line;
        StringBuilder sb =  new StringBuilder();
        try {
            while ((line = rd.readLine()) != null) {
                sb.append(line);
            }
            rd.close();

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String contentOfMyInputStream = sb.toString();
        return contentOfMyInputStream;
    }

//Call the above method with your origin and destination latitude and longitude.

For example:

  getDistance(23.0225,72.5714,21.1702,72.8311);

Answer 2

you will get the difference of two lat long using bellow method.

public float getDistance(double lat1, double lon1, double lat2, double lon2) {
               android.location.Location homeLocation = new android.location.Location("");
                homeLocation .setLatitude(lat1);
                homeLocation .setLongitude(lon1);

                android.location.Location targetLocation = new android.location.Location("");
                targetLocation .setLatitude(lat2);
                targetLocation .setLongitude(lon2);

                 float distanceInMeters =  targetLocation.distanceTo(homeLocation);
                 return distanceInMeters ;
}

if you want distance in km please convert it to km.