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 Path Project Structure
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.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 |
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:
This brings an end to this tutorial. You can download the final project from the link below, add your own Google Map API key.