Android Geolocation API and Google Maps

Part 1: Create a basic Android Map Application

Follow the tutorial to create a simple Android project with Google Maps:

https://developers.google.com/maps/documentation/android-api/start

Part 2: Accessing the Map object and showing User's location

1. Make your activity implement the OnMapReadyCallback interface. This interface will allow you to know when the map is ready to use when the onMapReady method is called.

2. Retrieve SupportMapFragment and retrieve the map asynchronously sending the activity as parameter to be the callback:

   // 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 );

3. Create another field for the GoogleMap object on the Activity and save it when the onMapReady method is called:

   @Override
   public void onMapReady( GoogleMap googleMap )
   {
       this.googleMap = googleMap;
   }

4. Create a method that shows your current location and another to check for the user permission to access the location with the following code:

       public void showMyLocation()
       {
          if ( googleMap != null )
          {
              String[] permissions = { android.Manifest.permission.ACCESS_FINE_LOCATION,
                  android.Manifest.permission.ACCESS_COARSE_LOCATION };
              if ( hasPermissions( this, permissions ) )
              {
                  googleMap.setMyLocationEnabled( true );
       
                  Location lastLocation = LocationServices.FusedLocationApi.getLastLocation( googleApiClient );
                  if ( lastLocation != null )
                  {
                      addMarkerAndZoom( lastLocation, "My Location", 15 );
                  }
              }
              else
              {
       ActivityCompat.requestPermissions( activity, permissions, ACCESS_LOCATION_PERMISSION_CODE );
              }
          }
       }
       
       public static boolean hasPermissions( Context context, String[] permissions )
       {
          for ( String permission : permissions )
          {
              if ( ContextCompat.checkSelfPermission( context, permission ) == PackageManager.PERMISSION_DENIED )
              {
                  return false;
              }
          }
          return true;
       }

5. Create the method addMarkerAndZoom in the main Activity:

   public void addMarkerAndZoom( Location location, String title, int zoom  )
   {
      LatLng myLocation = new LatLng( location.getLatitude(), location.getLongitude() );
      googleMap.addMarker( new MarkerOptions().position( myLocation ).title( title ) );
      googleMap.moveCamera( CameraUpdateFactory.newLatLngZoom( myLocation, zoom ) );
   }

6. Override the onRequestPermissionsResult method and check for the ACCESS_LOCATION_PERMISSION_CODE with the following code:

    @Override
    public void onRequestPermissionsResult( int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults )
    {
       for ( int grantResult : grantResults )
       {
           if ( grantResult == -1 )
           {
               return;
           }
       }
       switch ( requestCode )
       {
           case ACCESS_LOCATION_PERMISSION_CODE:
               showMyLocation();
               break;
           default:
               super.onRequestPermissionsResult( requestCode, permissions, grantResults );
       }
    }

7. Test the application on a real device and make sure your location is shown.

Part 3: Using the GoogleApiClient and Geolocation API

1. Add a button at the bottom of the map with the label “find address”

2. Include the Google Play Services Library on your build.gradle file:

       compile 'com.google.android.gms:play-services:10.2.1'

3. Declare a GoogleApiClient field on the main activity and instantiate it on the onCreate method:

       //Configure Google Maps API Objects
       googleApiClient = new GoogleApiClient.Builder( this ).addConnectionCallbacks( this ).
       addOnConnectionFailedListener( this ).addApi( LocationServices.API ).build();
       locationRequest.setInterval( 10000 );
       locationRequest.setFastestInterval( 5000 );
       locationRequest.setPriority( LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY );
       googleApiClient.connect();

4. Make the main Activity Implement the GoogleApiClient.ConnectionCallbacks with the following code:

       @Override
       public void onConnected( @Nullable Bundle bundle )
       {
         LocationServices.FusedLocationApi.requestLocationUpdates( googleApiClient, locationRequest,
                                                                    new LocationListener()
                                                                    {
                                                                        @Override
                                                                        public void onLocationChanged( Location location )
                                                                        {
                                                                            showMyLocation();
                                                                            stopLocationUpdates();
                                                                        }
                                                                    } );
       
       }
       
       @Override
       public void onConnectionSuspended( int i )
       {
          LocationServices.FusedLocationApi.removeLocationUpdates( googleApiClient, null);
       }
       
       public void stopLocationUpdates()
       {
          LocationServices.FusedLocationApi.removeLocationUpdates( googleApiClient, new LocationListener()
          {
              @Override
              public void onLocationChanged( Location location )
              {
       
              }
          } );
       }

5. Create a method that handles the onClick event from the Find Address button with the following code:

       public void onFindAddressClicked( View view )
       {
       startFetchAddressIntentService();
       }
       public void startFetchAddressIntentService()
       {
          Location lastLocation = LocationServices.FusedLocationApi.getLastLocation( googleApiClient );
          if ( lastLocation != null )
          {
              AddressResultReceiver addressResultReceiver = new AddressResultReceiver( new Handler() );
              addressResultReceiver.setAddressResultListener( new AddressResultListener()
              {
                  @Override
                  public void onAddressFound( final String address )
                  {
                      runOnUiThread( new Runnable()
                      {
                          @Override
                          public void run()
                          {
                              MapsActivity.this.address.setText( address );
                              MapsActivity.this.address.setVisibility( View.VISIBLE );
                          }
                      } );
       
       
                  }
              } );
              Intent intent = new Intent( this, FetchAddressIntentService.class );
              intent.putExtra( FetchAddressIntentService.RECEIVER, addressResultReceiver );
              intent.putExtra( FetchAddressIntentService.LOCATION_DATA_EXTRA, lastLocation );
              startService( intent );
          }
       }
       }

6. To be able to run the project you will need the following classes AddressResultReceiver, AddressResultListener and FetchAddressIntentService. In the following url you will be able to find a project that contains the missing classes:

   https://github.com/sancarbar/android-maps-demo

7. Include the service you created in the AndroidManifest file (below the closing tag):

       <service
        android:name=".FetchAddressIntentService"
        android:exported="false" />
        

Part 4: Implement Add location feature

1. Add a floating action button to the Maps view at the right bottom.

2. Implement the onClick listener for the Add Button that redirects to another Activity where the user can add a new Location to the map. A location has a name, a description and a geolocation (longitude and latitude).

3. Create a form that captures the Location data and add a save button that validates the form and submits the data.

4. Once the user creates a new Location then the Application should take you back to the map and displayed the created location.