How to Implement Google Maps Directions API in Android

Integrate the Google Maps Directions API

• Ensure you have included the Google Play Services in your project by adding the appropriate dependencies in your `build.gradle` file. This typically includes:

  implementation 'com.google.android.gms:play-services-maps:18.0.2'
  implementation 'com.google.android.gms:play-services-location:21.0.1'
  

 

• Set up the map fragment in your `activity_main.xml` layout to load the Google Map:

  <fragment
      android:id="@+id/map"
      android:name="com.google.android.gms.maps.SupportMapFragment"
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
  

Enable API Calls and Request Permissions

• Ensure the necessary permissions are requested in `AndroidManifest.xml`:

  <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
  <uses-permission android:name="android.permission.INTERNET" />
  
  <meta-data
      android:name="com.google.android.geo.API_KEY"
      android:value="@string/google_maps_key" />
  

 

• Request location permissions in your Activity to ensure your app can access location services when needed:

  ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_LOCATION_PERMISSION);
  

Fetch Directions API Data

• Construct a URL for the Google Maps Directions API and make a network call to fetch directions. You can use `OkHttpClient` for network calls:

  String origin = "origin=START_LAT,START_LONG";
  String destination = "destination=END_LAT,END_LONG";
  String apiKey = "key=YOUR_API_KEY";
  String url = "https://maps.googleapis.com/maps/api/directions/json?" + origin + "&" + destination + "&" + apiKey;
  
  OkHttpClient client = new OkHttpClient();
  Request request = new Request.Builder().url(url).build();
  client.newCall(request).enqueue(new Callback() {
      @Override
      public void onFailure(Call call, IOException e) {
          e.printStackTrace();
      }
  
      @Override
      public void onResponse(Call call, Response response) throws IOException {
          if (response.isSuccessful()) {
              final String jsonResponse = response.body().string();
              runOnUiThread(new Runnable() {
                  @Override
                  public void run() {
                      // Parse and display directions
                  }
              });
          }
      }
  });
  

Parse and Display Directions

• Parse the JSON response to extract necessary route information. It is useful to parse the steps and display them in a `Polyline` on your map. Utilize a helper class or library to parse JSON objects and responses for easier access.

  JSONObject jsonObject = new JSONObject(jsonResponse);
  JSONArray routes = jsonObject.getJSONArray("routes");
  JSONObject route = routes.getJSONObject(0);
  JSONObject overviewPolyline = route.getJSONObject("overview_polyline");
  String encodedString = overviewPolyline.getString("points");
  List<LatLng> points = PolyUtil.decode(encodedString);
  
  // Drawing polyline in the Google Map
  PolylineOptions polylineOptions = new PolylineOptions().addAll(points);
  googleMap.addPolyline(polylineOptions);
  

 

• Use markers to indicate start and end locations on the map:

  googleMap.addMarker(new MarkerOptions().position(START_LAT_LNG).title("Start Location"));
  googleMap.addMarker(new MarkerOptions().position(END_LAT_LNG).title("End Location"));
  googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(START_LAT_LNG, 10));
  

Troubleshoot Common Issues

• Verify that the API key is correctly configured in your `Strings.xml` file and that the Directions API has been enabled in the Google Cloud Platform.

 

• Ensure the app has network permissions and access to location services, which are critical for fetching the route and displaying it correctly.