Android Google Map – Drawing Route Between two points

Filed Under: Android

In this tutorial, we’ll be creating an android application that draws a possible google map route between two points. We’ll be using Google Maps Directions API in our application.

Android Google Map – Drawing Route

Create a new Google Map API Key from the API console using the steps demonstrated in this tutorial.

Create a New Android Studio Project and select the template as Google Maps Activity. Add the API key inside the google_maps_api.xml file that resides inside debug->res->values folder

This is how the application should look if you’re using the latest Android Studio.
android google maps drawing route between two points

Android Google Maps Drawing Path Project Structure

drawing path between two points in google maps android

The DirectionsJSONParser.java file is the one that parses the locations and returns the route. decodePoly() method is then invoked to get the polyline data that’s later drawn on the map.

Android Google Maps Drawing Route Code

The MainActivity.java code is given below.


public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;
    ArrayList markerPoints= new ArrayList();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        LatLng sydney = new LatLng(-34, 151);
        //mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(sydney, 16));

        mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
            @Override
            public void onMapClick(LatLng latLng) {

                if (markerPoints.size() > 1) {
                    markerPoints.clear();
                    mMap.clear();
                }

                // Adding new item to the ArrayList
                markerPoints.add(latLng);

                // Creating MarkerOptions
                MarkerOptions options = new MarkerOptions();

                // Setting the position of the marker
                options.position(latLng);

                if (markerPoints.size() == 1) {
                    options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
                } else if (markerPoints.size() == 2) {
                    options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
                }

                // Add new marker to the Google Map Android API V2
                mMap.addMarker(options);

                // Checks, whether start and end locations are captured
                if (markerPoints.size() >= 2) {
                    LatLng origin = (LatLng) markerPoints.get(0);
                    LatLng dest = (LatLng) markerPoints.get(1);

                    // Getting URL to the Google Directions API
                    String url = getDirectionsUrl(origin, dest);

                    DownloadTask downloadTask = new DownloadTask();

                    // Start downloading json data from Google Directions API
                    downloadTask.execute(url);
                }

            }
        });

    }

    private class DownloadTask extends AsyncTask {

        @Override
        protected String doInBackground(String... url) {

            String data = "";

            try {
                data = downloadUrl(url[0]);
            } catch (Exception e) {
                Log.d("Background Task", e.toString());
            }
            return data;
        }

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

            ParserTask parserTask = new ParserTask();


            parserTask.execute(result);

        }
    }

    private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap>>> {

        // Parsing the data in non-ui thread
        @Override
        protected List<List<HashMap>> doInBackground(String... jsonData) {

            JSONObject jObject;
            List<List<HashMap>> routes = null;

            try {
                jObject = new JSONObject(jsonData[0]);
                DirectionsJSONParser parser = new DirectionsJSONParser();

                routes = parser.parse(jObject);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return routes;
        }

        @Override
        protected void onPostExecute(List<List<HashMap>> result) {
            ArrayList points = null;
            PolylineOptions lineOptions = null;
            MarkerOptions markerOptions = new MarkerOptions();

            for (int i = 0; i < result.size(); i++) {
                points = new ArrayList();
                lineOptions = new PolylineOptions();

                List<HashMap> path = result.get(i);

                for (int j = 0; j < path.size(); j++) {
                    HashMap point = path.get(j);

                    double lat = Double.parseDouble(point.get("lat"));
                    double lng = Double.parseDouble(point.get("lng"));
                    LatLng position = new LatLng(lat, lng);

                    points.add(position);
                }

                lineOptions.addAll(points);
                lineOptions.width(12);
                lineOptions.color(Color.RED);
                lineOptions.geodesic(true);

            }

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

    private String getDirectionsUrl(LatLng origin, LatLng dest) {

        // Origin of route
        String str_origin = "origin=" + origin.latitude + "," + origin.longitude;

        // Destination of route
        String str_dest = "destination=" + dest.latitude + "," + dest.longitude;

        // Sensor enabled
        String sensor = "sensor=false";
        String mode = "mode=driving";

        // Building the parameters to the web service
        String parameters = str_origin + "&" + str_dest + "&" + sensor + "&" + mode;

        // Output format
        String output = "json";

        // Building the url to the web service
        String url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters;
        

        return url;
    }

    private String downloadUrl(String strUrl) throws IOException {
        String data = "";
        InputStream iStream = null;
        HttpURLConnection urlConnection = null;
        try {
            URL url = new URL(strUrl);

            urlConnection = (HttpURLConnection) url.openConnection();

            urlConnection.connect();

            iStream = urlConnection.getInputStream();

            BufferedReader br = new BufferedReader(new InputStreamReader(iStream));

            StringBuffer sb = new StringBuffer();

            String line = "";
            while ((line = br.readLine()) != null) {
                sb.append(line);
            }

            data = sb.toString();

            br.close();

        } catch (Exception e) {
            Log.d("Exception", e.toString());
        } finally {
            iStream.close();
            urlConnection.disconnect();
        }
        return data;
    }
}

We’ve called an onMapClickListener on the google map object. It’s used to set a marker on the clicked location and store that location in an ArrayList. The ArrayList is used to store the source and destination markers only.
The getDirectionsUrl() is called the Directions API URL with the output and parameters as shown below.

"https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters;

The output variable holds a “json” string and the parameter string is created as:
String parameters = str_origin + "&" + str_dest + "&" + sensor + "&" + mode;

We’ve set the mode=driving in the current application.
The other modes of transport are:

  • driving (default)
  • walking
  • bicycling
  • transit

The output of the application is given below:

android google maps draw path

This brings an end to this tutorial. You can download the final project from the link below, add your own Google Map API key.

Comments

  1. Thomas Tsuma says:

    Hi , Im trying to understand your code since I am a beginner.
    Why do I keep getting this runtime error:
    java.lang.NullPointerException: Attempt to invoke interface method ‘int java.util.List.size()’ on a null object reference

    it has something to do with result being null

    1. Pankaj says:

      Yes, you can’t call methods on a “null” object. Check if the object is initialized properly.

  2. Prabeesh P says:

    I want to draw route between two points in map.But as per the above code I could only select two points in map, the direction doesn’t came.
    Is there any suggestions for me to solve .

  3. Vinod Kadiyan says:

    Dear

    I have gone through your tutorials of google map android. I am stuck to show journey route of train covered and remaining in two different colors. Second color overlapping on 1st one…

    2nd issue it is showing alternative route which I coded alternatives=false also but still showing extra lines…

    Please visit URL to have more information about issue…https://stackoverflow.com/questions/57495955/how-to-show-journey-of-train-reached-and-remaining-on-mobile-app

    I want little help to sort these small issues…

  4. survey says:

    polylineOptions = null

    why is it empty?

  5. Syed Reazul Elahee says:

    I want to draw route between more than two points. How can i do that ? Is it possible with a single call ?

  6. Bhavya Shah says:

    Any help with this?

    java.lang.NullPointerException: PolylineOptions cannot be null.
    at com.google.maps.api.android.lib6.common.n.a(:com.google.android.gms.dynamite_mapsdynamite@13280052@13.2.80 (040700-211705629):32)
    at com.google.maps.api.android.lib6.impl.dm.(:com.google.android.gms.dynamite_mapsdynamite@13280052@13.2.80 (040700-211705629):6)
    at com.google.maps.api.android.lib6.impl.bc.a(:com.google.android.gms.dynamite_mapsdynamite@13280052@13.2.80 (040700-211705629):80)
    at com.google.android.gms.maps.internal.l.a(:com.google.android.gms.dynamite_mapsdynamite@13280052@13.2.80 (040700-211705629):501)
    at fh.onTransact(:com.google.android.gms.dynamite_mapsdynamite@13280052@13.2.80 (040700-211705629):10)
    at android.os.Binder.transact(Binder.java:667)
    at com.google.android.gms.internal.maps.zza.transactAndReadException(Unknown Source:7)
    at com.google.android.gms.maps.internal.zzg.addPolyline(Unknown Source:9)
    at com.google.android.gms.maps.GoogleMap.addPolyline(Unknown Source:4)
    at com.example.hb.navdrawerapp.SecondFragment$ParserTask.onPostExecute(SecondFragment.java:169)
    at com.example.hb.navdrawerapp.SecondFragment$ParserTask.onPostExecute(SecondFragment.java:121)
    at android.os.AsyncTask.finish(AsyncTask.java:695)
    at android.os.AsyncTask.access$600(AsyncTask.java:180)
    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:712)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6669)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

    1. Vishal Singh says:

      Add your api key to url as mentioned below

      String url = “https://maps.googleapis.com/maps/api/directions/” + output + “?” + parameters +”&key=” +”YOUR KEY”;

  7. Bhavya Shah says:

    I want to use this inside fragment. I did this in my OnCreateView()-

    View rootView=inflater.inflate(R.layout.image1,container,false);
    mapFragment = (SupportMapFragment) getFragmentManager().findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    return rootView;

    And I am getting this error-
    java.lang.NullPointerException: Attempt to invoke virtual method ‘void com.google.android.gms.maps.SupportMapFragment.getMapAsync(com.google.android.gms.maps.OnMapReadyCallback)’ on a null object reference

  8. Bhavya Shah says:

    I am not getting an output. It just shows a map, that’s all.

  9. Vinod Singh says:

    Hi Anupam Chugh,

    Could you tell me after drawing a map between two locations,how to update a user position with respect to his moment? Can you help me please…….. Thank you!

  10. Benson says:

    DirectionsJSONParser is missing.

  11. Gift says:

    Morning

    when i run the app it crashes and the error points to this String str_dest = “destination=” + dest.latitude + “,” + dest.longitude;

  12. Alexander says:

    Hi, you are really helped me, but I’m getting errors:
    java.lang.NullPointerException: PolylineOptions cannot be null.
    why is this error?

    1. Anupam says:

      Please make sure that the class object is initialised properly.

    2. Tigran says:

      Hi, Did you solved the problem?

      1. Varun says:

        I am also facing the same issue. I Just downloaded and code, added my key and ran it.

      1. Jacito Duarte says:

        this route key is free??

  13. Andŕes Guachun says:

    Hi, the google directions have a cost?

  14. kritesh kabariya says:

    if i can 8 or 9 time in add point in polylineoption then give error you can try

    first get spinner and add 2 value driving and walking
    that add in mode value
    after select to change route

    that selection 7 or 8 time i sure give the error

  15. LeizaR says:

    i am here just to say i love it, work on the first time
    is there any way to get the distance from the route?

    1. Anupam says:

      Use the Google Distance API

  16. Keshav says:

    Where is DirectionJsonparser.java code?

  17. Amrut says:

    For me the route is not getting drawn, what could be the issue?

    1. Asmit Adak says:

      same here brother

    2. amila says:

      same here did you solved iT?

  18. erfan says:

    nice and clean . thanks

  19. Sjhivani says:

    Cant see a directional route between my marker points…getting a straight line instead..
    Please help me fix the issue

  20. fajarra says:

    i found error here,

    Error:Execution failed for task ‘:app:transformClassesWithDexForDebug’.
    > com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.dex.DexIndexOverflowException: method ID not in [0, 0xffff]: 65536

    what must i do ..?

    1. fajarra says:

      i solve my problem after migrate compileSdkVersion from 25 to 26. Thanks Anupam, its great….

      1. sudarsana says:

        please tell me i got same error how to solve it

        1. Debasish Ghosh says:

          firstly import this gradle :
          compile ‘com.android.support:multidex:1.0.0’

          then write
          defaultConfig {

          ………………………..
          …………………………
          multiDexEnabled true
          }

          it should be help for you…..

  21. Emil says:

    Hi, Can we mark for more than one locations?

  22. Amin says:

    Hello. thx for your great post. How can i add more than one location and add polyline for it ?

    1. harshit says:

      sir,did you got the solution for adding more than one marker

  23. kana says:

    Every thing is great, but it doesnt zooms at current location.. How to do that?? Please reply ASAP !

  24. lathiya bhautik says:

    i didn’t find DirectionsJSONParser file

  25. Anirudh Kaluri says:

    the for loop in onPostExecute isnt getting executed. Please tell me how.

    1. Anupam says:

      Perhaps the direction result isn’t being returned. Maybe you haven’t enabled the Direction API

    2. Akhilesh Kumar Shukla says:

      have u solved the issues

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