Seleziona il luogo attuale e mostra i dettagli su una mappa

Scopri come trovare la posizione attuale di un dispositivo Android e visualizzare i dettagli del luogo (un'attività o un altro punto d'interesse) in quella posizione. Segui questo tutorial per creare un'app per Android utilizzando Maps SDK for Android, Places SDK for Android e il provider di geolocalizzazione combinata nelle API di geolocalizzazione di Google Play Services.

Ottieni il codice

Clona o scarica il repository di esempi v2 dell'API Google Maps Android da GitHub.

Visualizza la versione Java dell'attività:

    // Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.example.currentplacedetailsonmap;

import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.util.TypedValue;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.libraries.places.api.Places;
import com.google.android.libraries.places.api.model.CircularBounds;
import com.google.android.libraries.places.api.model.Place;
import com.google.android.libraries.places.api.net.PlacesClient;
import com.google.android.libraries.places.api.net.SearchNearbyRequest;
import com.google.android.libraries.places.api.net.SearchNearbyResponse;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/** An activity that displays a map showing the place at the device's current location. */
public class MapsActivityCurrentPlace extends AppCompatActivity implements OnMapReadyCallback {

    private static final String TAG = MapsActivityCurrentPlace.class.getSimpleName();
    private GoogleMap map;
    private CameraPosition cameraPosition;

    // The entry point to the Places API.
    private PlacesClient placesClient;

    // The entry point to the Fused Location Provider.
    private FusedLocationProviderClient fusedLocationProviderClient;

    // A default location (Sydney, Australia) and default zoom to use when location permission is
    // not granted.
    private final LatLng defaultLocation = new LatLng(-33.8523341, 151.2106085);
    private static final int DEFAULT_ZOOM = 15;
    private static final int PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1;
    private boolean locationPermissionGranted;

    // The geographical location where the device is currently located. That is, the last-known
    // location retrieved by the Fused Location Provider or set via long press.
    Location lastKnownLocation;

    // Keys for storing activity state.
    private static final String KEY_CAMERA_POSITION = "camera_position";
    private static final String KEY_LOCATION = "location";

    // Used for selecting the current place.
    private static final int M_MAX_ENTRIES = 5;
    private static final double SEARCH_RADIUS_METERS = 100.0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Retrieve location and camera position from saved instance state.
        if (savedInstanceState != null) {
            lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION);
            cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION);
        }

        // Retrieve the content view that renders the map.
        setContentView(R.layout.activity_maps);

        ViewCompat.setOnApplyWindowInsetsListener(
                getWindow().getDecorView(),
                (v, insets) -> {
                    Insets systemBars =
                            insets.getInsets(
                                    WindowInsetsCompat.Type.systemBars()
                                            | WindowInsetsCompat.Type.displayCutout());
                    View actionBarContainer =
                            getWindow()
                                    .getDecorView()
                                    .findViewById(androidx.appcompat.R.id.action_bar_container);
                    if (actionBarContainer != null) {
                        actionBarContainer.setPadding(
                                actionBarContainer.getPaddingLeft(),
                                systemBars.top,
                                actionBarContainer.getPaddingRight(),
                                actionBarContainer.getPaddingBottom());
                    }
                    TypedValue typedValue = new TypedValue();
                    int actionBarHeight =
                            getTheme()
                                            .resolveAttribute(
                                                    android.R.attr.actionBarSize, typedValue, true)
                                    ? TypedValue.complexToDimensionPixelSize(
                                            typedValue.data, getResources().getDisplayMetrics())
                                    : 0;
                    if (map != null) {
                        map.setPadding(0, systemBars.top + actionBarHeight, 0, systemBars.bottom);
                    }
                    return insets;
                });
        // Construct a PlacesClient
        Places.initializeWithNewPlacesApiEnabled(getApplicationContext(), BuildConfig.MAPS_API_KEY);
        placesClient = Places.createClient(this);

        // Construct a FusedLocationProviderClient.
        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);

        // Build the map.
        SupportMapFragment mapFragment =
                (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }


    /** Saves the state of the map when the activity is paused. */
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        if (map != null) {
            outState.putParcelable(KEY_CAMERA_POSITION, map.getCameraPosition());
            outState.putParcelable(KEY_LOCATION, lastKnownLocation);
        }
        super.onSaveInstanceState(outState);
    }


    /**
     * Sets up the options menu.
     *
     * @param menu The options menu.
     * @return Boolean.
     */
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.current_place_menu, menu);
        return true;
    }

    /**
     * Handles a click on the menu option to get a place.
     *
     * @param item The menu item to handle.
     * @return Boolean.
     */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == R.id.option_get_place) {
            showCurrentPlace();
        }
        return true;
    }


    /**
     * Manipulates the map when it's available. This callback is triggered when the map is ready to
     * be used.
     */
    @Override
    public void onMapReady(GoogleMap map) {
        this.map = map;

        // Use a custom info window adapter to handle multiple lines of text in the
        // info window contents.
        this.map.setInfoWindowAdapter(
                new GoogleMap.InfoWindowAdapter() {

                    @Override
                    // Return null here, so that getInfoContents() is called next.
                    public View getInfoWindow(Marker arg0) {
                        return null;
                    }

                    @Override
                    public View getInfoContents(Marker marker) {
                        // Inflate the layouts for the info window, title and snippet.
                        View infoWindow =
                                getLayoutInflater()
                                        .inflate(
                                                R.layout.custom_info_contents,
                                                (FrameLayout) findViewById(R.id.map),
                                                false);

                        TextView title = infoWindow.findViewById(R.id.title);
                        title.setText(marker.getTitle());

                        TextView snippet = infoWindow.findViewById(R.id.snippet);
                        snippet.setText(marker.getSnippet());

                        return infoWindow;
                    }
                });

        // Allow moving the current location with a long press on the map to easily
        // demo and discover nearby places anywhere in the world.
        this.map.setOnMapLongClickListener(this::setCustomLocation);

        // Prompt the user for permission.
        getLocationPermission();

        WindowInsetsCompat rootInsets = ViewCompat.getRootWindowInsets(getWindow().getDecorView());
        if (rootInsets != null) {
            Insets systemBars =
                    rootInsets.getInsets(
                            WindowInsetsCompat.Type.systemBars()
                                    | WindowInsetsCompat.Type.displayCutout());
            TypedValue typedValue = new TypedValue();
            int actionBarHeight =
                    getTheme().resolveAttribute(android.R.attr.actionBarSize, typedValue, true)
                            ? TypedValue.complexToDimensionPixelSize(
                                    typedValue.data, getResources().getDisplayMetrics())
                            : 0;
            this.map.setPadding(0, systemBars.top + actionBarHeight, 0, systemBars.bottom);
        }

        // Turn on the My Location layer and the related control on the map.
        updateLocationUI();

        // Get the current location of the device and set the position of the map.
        getDeviceLocation();
    }


    /** Gets the current location of the device, and positions the map's camera. */
    private void getDeviceLocation() {
        /*
         * Get the best and most recent location of the device, which may be null in rare
         * cases when a location is not available.
         */
        try {
            if (locationPermissionGranted) {
                Task<Location> locationResult = fusedLocationProviderClient.getLastLocation();
                locationResult.addOnCompleteListener(
                        this,
                        new OnCompleteListener<Location>() {
                            @Override
                            public void onComplete(@NonNull Task<Location> task) {
                                if (task.isSuccessful()) {
                                    // Set the map's camera position to the current location of the
                                    // device.
                                    lastKnownLocation = task.getResult();
                                    if (lastKnownLocation != null) {
                                        map.moveCamera(
                                                CameraUpdateFactory.newLatLngZoom(
                                                        new LatLng(
                                                                lastKnownLocation.getLatitude(),
                                                                lastKnownLocation.getLongitude()),
                                                        DEFAULT_ZOOM));
                                    }
                                } else {
                                    Log.d(TAG, "Current location is null. Using defaults.");
                                    Log.e(TAG, "Exception: %s", task.getException());
                                    map.moveCamera(
                                            CameraUpdateFactory.newLatLngZoom(
                                                    defaultLocation, DEFAULT_ZOOM));
                                    map.getUiSettings().setMyLocationButtonEnabled(false);
                                }
                            }
                        });
            }
        } catch (SecurityException e) {
            Log.e("Exception: %s", e.getMessage(), e);
        }
    }


    /** Prompts the user for permission to use the device location. */
    private void getLocationPermission() {
        /*
         * Request location permission, so that we can get the location of the
         * device. The result of the permission request is handled by a callback,
         * onRequestPermissionsResult.
         */
        if (ContextCompat.checkSelfPermission(
                        this.getApplicationContext(),
                        android.Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            locationPermissionGranted = true;
        } else {
            ActivityCompat.requestPermissions(
                    this,
                    new String[] {android.Manifest.permission.ACCESS_FINE_LOCATION},
                    PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
        }
    }


    /** Handles the result of the request for location permissions. */
    @Override
    public void onRequestPermissionsResult(
            int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        locationPermissionGranted = false;
        if (requestCode
                == PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION) { // If request is cancelled, the
            // result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                locationPermissionGranted = true;
            }
        } else {
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
        updateLocationUI();
    }


    /**
     * UI representation of a place item to display in the selection dialog and map marker.
     *
     * <p>It is good practice to decouple the external data/backend model ({@link Place}) from the
     * UI layer. The UI should be as free of logic as possible: it receives presentation-ready data
     * (non-null coordinates, ready-to-display title and snippet strings) so that dialogs and map
     * overlays remain simple, predictable, and testable.
     */
    static class PlaceItemUiModel {
        final String title;
        final String snippet;
        final LatLng position;

        PlaceItemUiModel(String title, String snippet, LatLng position) {
            this.title = title;
            this.snippet = snippet;
            this.position = position;
        }
    }

    /**
     * Maps an external {@link Place} domain model into a display-ready {@link PlaceItemUiModel}.
     *
     * <p>The mapper encapsulates all data normalization, default value fallbacks (such as fallback
     * titles), and string formatting (such as appending third-party attributions to the address).
     * Keeping this transformation logic in the mapper prevents business and formatting logic from
     * leaking into the UI components. Returns {@code null} if essential coordinates are missing.
     */
    private PlaceItemUiModel toUiModel(Place place) {
        return toUiModel(place, getString(R.string.default_info_title));
    }

    static PlaceItemUiModel toUiModel(Place place, String defaultTitle) {
        if (place.getLocation() == null) {
            return null;
        }
        String title = place.getDisplayName() != null ? place.getDisplayName() : defaultTitle;

        StringBuilder snippet = new StringBuilder();
        if (place.getFormattedAddress() != null) {
            snippet.append(place.getFormattedAddress());
        }
        if (place.getAttributions() != null && !place.getAttributions().isEmpty()) {
            if (snippet.length() > 0) {
                snippet.append("\n");
            }
            snippet.append(String.join("\n", place.getAttributions()));
        }
        return new PlaceItemUiModel(title, snippet.toString(), place.getLocation());
    }


    /**
     * Prompts the user to select the current place from a list of likely places, and shows the
     * current place on the map - provided the user has granted location permission.
     */
    private void showCurrentPlace() {
        if (map == null) {
            return;
        }

        if (lastKnownLocation != null && "manual".equals(lastKnownLocation.getProvider())) {
            locationPermissionGranted = true;
        }

        if (locationPermissionGranted) {
            // Use fields to define the data types to return.
            List<Place.Field> placeFields =
                    Arrays.asList(
                            Place.Field.DISPLAY_NAME,
                            Place.Field.FORMATTED_ADDRESS,
                            Place.Field.LOCATION);

            // Search around the device's last-known location, falling back to the center of the
            // map if the location is not available yet.
            LatLng center =
                    lastKnownLocation != null
                            ? new LatLng(
                                    lastKnownLocation.getLatitude(),
                                    lastKnownLocation.getLongitude())
                            : map.getCameraPosition().target;
            CircularBounds searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS);

            // Use the builder to create a SearchNearbyRequest that returns the closest places
            // first.
            SearchNearbyRequest request =
                    SearchNearbyRequest.builder(searchArea, placeFields)
                            .setMaxResultCount(M_MAX_ENTRIES)
                            .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE)
                            .build();

            // Get the likely places - that is, the businesses and other points of interest that
            // are closest to the device's current location.
            final Task<SearchNearbyResponse> placeResult = placesClient.searchNearby(request);
            placeResult.addOnCompleteListener(
                    new OnCompleteListener<SearchNearbyResponse>() {
                        @Override
                        public void onComplete(@NonNull Task<SearchNearbyResponse> task) {
                            if (task.isSuccessful() && task.getResult() != null) {
                                List<Place> responsePlaces = task.getResult().getPlaces();
                                int count = Math.min(responsePlaces.size(), M_MAX_ENTRIES);
                                List<PlaceItemUiModel> likelyPlaces = new ArrayList<>();
                                for (int i = 0; i < count; i++) {
                                    PlaceItemUiModel model = toUiModel(responsePlaces.get(i));
                                    if (model != null) {
                                        likelyPlaces.add(model);
                                    }
                                }

                                // Show a dialog offering the user the list of likely places, and
                                // add a marker at the selected place.
                                MapsActivityCurrentPlace.this.openPlacesDialog(likelyPlaces);
                            } else {
                                Log.e(TAG, "Exception: %s", task.getException());
                            }
                        }
                    });
        } else {
            // The user has not granted permission.
            Log.i(TAG, "The user did not grant location permission.");

            // Add a default marker, because the user hasn't selected a place.
            map.addMarker(
                    new MarkerOptions()
                            .title(getString(R.string.default_info_title))
                            .position(defaultLocation)
                            .snippet(getString(R.string.default_info_snippet)));

            // Prompt the user for permission.
            getLocationPermission();
        }
    }


    /** Displays a form allowing the user to select a place from a list of likely places. */
    void openPlacesDialog(List<PlaceItemUiModel> likelyPlaces) {
        if (likelyPlaces.isEmpty()) {
            Toast.makeText(
                            this,
                            "No places found nearby. Long-press on the map to choose another location.",
                            Toast.LENGTH_LONG)
                    .show();
            return;
        }
        // Ask the user to choose the place where they are now.
        DialogInterface.OnClickListener listener =
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // The "which" argument contains the position of the selected item.
                        PlaceItemUiModel selectedPlace = likelyPlaces.get(which);

                        // Add a marker for the selected place, with an info window
                        // showing information about that place.
                        map.addMarker(
                                new MarkerOptions()
                                        .title(selectedPlace.title)
                                        .position(selectedPlace.position)
                                        .snippet(selectedPlace.snippet));

                        // Position the map's camera at the location of the marker.
                        map.moveCamera(
                                CameraUpdateFactory.newLatLngZoom(
                                        selectedPlace.position, DEFAULT_ZOOM));
                    }
                };

        // Display the dialog.
        String[] titles = new String[likelyPlaces.size()];
        for (int i = 0; i < likelyPlaces.size(); i++) {
            titles[i] = likelyPlaces.get(i).title;
        }
        new AlertDialog.Builder(this)
                .setTitle(R.string.pick_place)
                .setItems(titles, listener)
                .show();
    }


    /** Updates the map's UI settings based on whether the user has granted location permission. */
    private void updateLocationUI() {
        if (map == null) {
            return;
        }
        try {
            if (locationPermissionGranted) {
                map.setMyLocationEnabled(true);
                map.getUiSettings().setMyLocationButtonEnabled(true);
            } else {
                map.setMyLocationEnabled(false);
                map.getUiSettings().setMyLocationButtonEnabled(false);
                lastKnownLocation = null;
            }
        } catch (SecurityException e) {
            Log.e("Exception: %s", e.getMessage());
        }
    }


    /** Updates the current location and searches for places around the specified coordinate. */
    void setCustomLocation(LatLng latLng) {
        Location location = new Location("manual");
        location.setLatitude(latLng.latitude);
        location.setLongitude(latLng.longitude);
        lastKnownLocation = location;
        if (map != null) {
            map.animateCamera(CameraUpdateFactory.newLatLng(latLng));
        }
        showCurrentPlace();
    }
}

Visualizza la versione Kotlin dell'attività:

    // Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.example.currentplacedetailsonmap

import android.Manifest
import android.annotation.SuppressLint
import android.content.DialogInterface
import android.content.pm.PackageManager
import android.location.Location
import android.os.Bundle
import android.util.Log
import android.util.TypedValue
import android.view.Menu
import android.view.MenuItem
import android.view.View
import android.widget.FrameLayout
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
import com.google.android.gms.location.FusedLocationProviderClient
import com.google.android.gms.location.LocationServices
import com.google.android.gms.maps.CameraUpdateFactory
import com.google.android.gms.maps.GoogleMap
import com.google.android.gms.maps.GoogleMap.InfoWindowAdapter
import com.google.android.gms.maps.OnMapReadyCallback
import com.google.android.gms.maps.SupportMapFragment
import com.google.android.gms.maps.model.CameraPosition
import com.google.android.gms.maps.model.LatLng
import com.google.android.gms.maps.model.Marker
import com.google.android.gms.maps.model.MarkerOptions
import com.google.android.libraries.places.api.Places
import com.google.android.libraries.places.api.model.CircularBounds
import com.google.android.libraries.places.api.model.Place
import com.google.android.libraries.places.api.net.PlacesClient
import com.google.android.libraries.places.api.net.SearchNearbyRequest

/**
 * An activity that displays a map showing the place at the device's current location.
 */
class MapsActivityCurrentPlace :
    AppCompatActivity(),
    OnMapReadyCallback {
    private var map: GoogleMap? = null
    private var cameraPosition: CameraPosition? = null
    internal var selectedMarker: Marker? = null

    // The entry point to the Places API.
    private lateinit var placesClient: PlacesClient

    // The entry point to the Fused Location Provider.
    private lateinit var fusedLocationProviderClient: FusedLocationProviderClient

    // A default location (Sydney, Australia) and default zoom to use when location permission is
    // not granted.
    private val defaultLocation = LatLng(-33.8523341, 151.2106085)
    private var locationPermissionGranted = false

    // The geographical location where the device is currently located. That is, the last-known
    // location retrieved by the Fused Location Provider or set via long press.
    internal var lastKnownLocation: Location? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Retrieve location and camera position from saved instance state.
        if (savedInstanceState != null) {
            lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION)
            cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION)
        }

        // Retrieve the content view that renders the map.
        setContentView(R.layout.activity_maps)

        ViewCompat.setOnApplyWindowInsetsListener(window.decorView) { _, insets ->
            val systemBars = insets.getInsets(
                WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout(),
            )
            val actionBarContainer = window.decorView.findViewById<View>(androidx.appcompat.R.id.action_bar_container)
            actionBarContainer?.setPadding(
                actionBarContainer.paddingLeft,
                systemBars.top,
                actionBarContainer.paddingRight,
                actionBarContainer.paddingBottom,
            )
            val typedValue = TypedValue()
            val actionBarHeight = if (theme.resolveAttribute(android.R.attr.actionBarSize, typedValue, true)) {
                TypedValue.complexToDimensionPixelSize(typedValue.data, resources.displayMetrics)
            } else {
                0
            }
            map?.setPadding(0, systemBars.top + actionBarHeight, 0, systemBars.bottom)
            insets
        }
        // Construct a PlacesClient
        Places.initializeWithNewPlacesApiEnabled(applicationContext, BuildConfig.MAPS_API_KEY)
        placesClient = Places.createClient(this)

        // Construct a FusedLocationProviderClient.
        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this)

        // Build the map.
        val mapFragment = supportFragmentManager
            .findFragmentById(R.id.map) as SupportMapFragment?
        mapFragment?.getMapAsync(this)
    }

    /**
     * Saves the state of the map when the activity is paused.
     */
    override fun onSaveInstanceState(outState: Bundle) {
        map?.let { map ->
            outState.putParcelable(KEY_CAMERA_POSITION, map.cameraPosition)
            outState.putParcelable(KEY_LOCATION, lastKnownLocation)
        }
        super.onSaveInstanceState(outState)
    }

    /**
     * Sets up the options menu.
     * @param menu The options menu.
     * @return Boolean.
     */
    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        menuInflater.inflate(R.menu.current_place_menu, menu)
        return true
    }

    /**
     * Handles a click on the menu option to get a place.
     * @param item The menu item to handle.
     * @return Boolean.
     */
    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        if (item.itemId == R.id.option_get_place) {
            showCurrentPlace()
        }
        return true
    }

    /**
     * Manipulates the map when it's available.
     * This callback is triggered when the map is ready to be used.
     */
    override fun onMapReady(map: GoogleMap) {
        this.map = map

        // Use a custom info window adapter to handle multiple lines of text in the
        // info window contents.
        this.map?.setInfoWindowAdapter(object : InfoWindowAdapter {
            // Return null here, so that getInfoContents() is called next.
            override fun getInfoWindow(arg0: Marker): View? = null

            override fun getInfoContents(marker: Marker): View {
                // Inflate the layouts for the info window, title and snippet.
                val infoWindow = layoutInflater.inflate(
                    R.layout.custom_info_contents,
                    findViewById<FrameLayout>(R.id.map),
                    false,
                )
                val title = infoWindow.findViewById<TextView>(R.id.title)
                title.text = marker.title
                val snippet = infoWindow.findViewById<TextView>(R.id.snippet)
                snippet.text = marker.snippet
                return infoWindow
            }
        })

        // Allow moving the current location with a long press on the map to easily
        // demo and discover nearby places anywhere in the world.
        this.map?.setOnMapLongClickListener { latLng ->
            setCustomLocation(latLng)
        }

        // Prompt the user for permission.
        getLocationPermission()

        val insets = ViewCompat.getRootWindowInsets(window.decorView)
            ?.getInsets(WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout())
        val topInset = insets?.top ?: 0
        val bottomInset = insets?.bottom ?: 0
        val typedValue = TypedValue()
        val actionBarHeight = if (theme.resolveAttribute(android.R.attr.actionBarSize, typedValue, true)) {
            TypedValue.complexToDimensionPixelSize(typedValue.data, resources.displayMetrics)
        } else {
            0
        }
        this.map?.setPadding(0, topInset + actionBarHeight, 0, bottomInset)

        // Turn on the My Location layer and the related control on the map.
        updateLocationUI()

        // Get the current location of the device and set the position of the map.
        getDeviceLocation()
    }

    /**
     * Gets the current location of the device, and positions the map's camera.
     */
    @SuppressLint("MissingPermission")
    private fun getDeviceLocation() {
        /*
         * Get the best and most recent location of the device, which may be null in rare
         * cases when a location is not available.
         */
        try {
            if (locationPermissionGranted) {
                val locationResult = fusedLocationProviderClient.lastLocation
                locationResult.addOnCompleteListener(this) { task ->
                    if (task.isSuccessful) {
                        // Set the map's camera position to the current location of the device.
                        lastKnownLocation = task.result
                        if (lastKnownLocation != null) {
                            map?.moveCamera(
                                CameraUpdateFactory.newLatLngZoom(
                                    LatLng(
                                        lastKnownLocation!!.latitude,
                                        lastKnownLocation!!.longitude,
                                    ),
                                    DEFAULT_ZOOM.toFloat(),
                                ),
                            )
                        }
                    } else {
                        Log.d(TAG, "Current location is null. Using defaults.")
                        Log.e(TAG, "Exception: %s", task.exception)
                        map?.moveCamera(
                            CameraUpdateFactory
                                .newLatLngZoom(defaultLocation, DEFAULT_ZOOM.toFloat()),
                        )
                        map?.uiSettings?.isMyLocationButtonEnabled = false
                    }
                }
            }
        } catch (e: SecurityException) {
            Log.e("Exception: %s", e.message, e)
        }
    }

    /**
     * Prompts the user for permission to use the device location.
     */
    private fun getLocationPermission() {
        /*
         * Request location permission, so that we can get the location of the
         * device. The result of the permission request is handled by a callback,
         * onRequestPermissionsResult.
         */
        if (ContextCompat.checkSelfPermission(
                this.applicationContext,
                Manifest.permission.ACCESS_FINE_LOCATION,
            )
            == PackageManager.PERMISSION_GRANTED
        ) {
            locationPermissionGranted = true
        } else {
            ActivityCompat.requestPermissions(
                this,
                arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
                PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION,
            )
        }
    }

    /**
     * Handles the result of the request for location permissions.
     */
    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
        locationPermissionGranted = false
        when (requestCode) {
            PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION -> {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.isNotEmpty() &&
                    grantResults[0] == PackageManager.PERMISSION_GRANTED
                ) {
                    locationPermissionGranted = true
                }
            }

            else -> super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        }
        updateLocationUI()
    }

    private fun Place.toUiModel(): PlaceItemUiModel? = toPlaceItemUiModel(this, getString(R.string.default_info_title))

    /**
     * Prompts the user to select the current place from a list of likely places, and shows the
     * current place on the map - provided the user has granted location permission.
     */
    private fun showCurrentPlace() {
        val map = map ?: return
        if (lastKnownLocation?.provider == "manual") {
            locationPermissionGranted = true
        }
        if (locationPermissionGranted) {
            // Use fields to define the data types to return.
            val placeFields = listOf(
                Place.Field.DISPLAY_NAME,
                Place.Field.FORMATTED_ADDRESS,
                Place.Field.LOCATION,
            )

            // Search around the device's last-known location, falling back to the center of
            // the map if the location is not available yet.
            val center = lastKnownLocation?.let { LatLng(it.latitude, it.longitude) }
                ?: map.cameraPosition.target
            val searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS)

            // Use the builder to create a SearchNearbyRequest that returns the closest places
            // first.
            val request = SearchNearbyRequest.builder(searchArea, placeFields)
                .setMaxResultCount(M_MAX_ENTRIES)
                .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE)
                .build()

            // Get the likely places - that is, the businesses and other points of interest that
            // are closest to the device's current location.
            val placeResult = placesClient.searchNearby(request)
            placeResult.addOnCompleteListener { task ->
                if (task.isSuccessful && task.result != null) {
                    val likelyPlaces = task.result.places
                        .take(M_MAX_ENTRIES)
                        .mapNotNull { it.toUiModel() }

                    // Show a dialog offering the user the list of likely places, and add a
                    // marker at the selected place.
                    openPlacesDialog(likelyPlaces)
                } else {
                    Log.e(TAG, "Exception: %s", task.exception)
                }
            }
        } else {
            // The user has not granted permission.
            Log.i(TAG, "The user did not grant location permission.")

            // Add a default marker, because the user hasn't selected a place.
            map.addMarker(
                MarkerOptions()
                    .title(getString(R.string.default_info_title))
                    .position(defaultLocation)
                    .snippet(getString(R.string.default_info_snippet)),
            )

            // Prompt the user for permission.
            getLocationPermission()
        }
    }

    /**
     * Displays a form allowing the user to select a place from a list of likely places.
     */
    internal fun openPlacesDialog(likelyPlaces: List<PlaceItemUiModel>) {
        if (likelyPlaces.isEmpty()) {
            Toast.makeText(
                this,
                "No places found nearby. Long-press on the map to choose another location.",
                Toast.LENGTH_LONG,
            ).show()
            return
        }
        // Ask the user to choose the place where they are now.
        val listener = DialogInterface.OnClickListener { _, which ->
            // The "which" argument contains the position of the selected item.
            val selectedPlace = likelyPlaces[which]

            // Add a marker for the selected place, with an info window
            // showing information about that place.
            selectedMarker = map?.addMarker(
                MarkerOptions()
                    .title(selectedPlace.title)
                    .position(selectedPlace.position)
                    .snippet(selectedPlace.snippet),
            )

            // Position the map's camera at the location of the marker.
            map?.moveCamera(
                CameraUpdateFactory.newLatLngZoom(
                    selectedPlace.position,
                    DEFAULT_ZOOM.toFloat(),
                ),
            )
        }

        // Display the dialog.
        val titles = likelyPlaces.map { it.title }.toTypedArray()
        AlertDialog.Builder(this)
            .setTitle(R.string.pick_place)
            .setItems(titles, listener)
            .show()
    }

    /**
     * Updates the map's UI settings based on whether the user has granted location permission.
     */
    @SuppressLint("MissingPermission")
    private fun updateLocationUI() {
        if (map == null) {
            return
        }
        try {
            if (locationPermissionGranted) {
                map?.isMyLocationEnabled = true
                map?.uiSettings?.isMyLocationButtonEnabled = true
            } else {
                map?.isMyLocationEnabled = false
                map?.uiSettings?.isMyLocationButtonEnabled = false
                lastKnownLocation = null
                getLocationPermission()
            }
        } catch (e: SecurityException) {
            Log.e("Exception: %s", e.message, e)
        }
    }

    /**
     * Updates the current location and searches for places around the specified coordinate.
     */
    internal fun setCustomLocation(latLng: LatLng) {
        val location = Location("manual").apply {
            latitude = latLng.latitude
            longitude = latLng.longitude
        }
        lastKnownLocation = location
        map?.animateCamera(CameraUpdateFactory.newLatLng(latLng))
        showCurrentPlace()
    }

    companion object {
        private val TAG = MapsActivityCurrentPlace::class.java.simpleName
        private const val DEFAULT_ZOOM = 15
        private const val PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1

        // Keys for storing activity state.
        private const val KEY_CAMERA_POSITION = "camera_position"
        private const val KEY_LOCATION = "location"

        // Used for selecting the current place.
        private const val M_MAX_ENTRIES = 5
        private const val SEARCH_RADIUS_METERS = 100.0
    }
}


/**
 * UI representation of a place item to display in the selection dialog and map marker.
 *
 * It is good practice to decouple the external data/backend model ([Place]) from the UI layer.
 * The UI should be as free of logic as possible: it receives presentation-ready data (non-null
 * coordinates, ready-to-display title and snippet strings) so that dialogs and map overlays
 * remain simple, predictable, and testable.
 */
internal data class PlaceItemUiModel(val title: String, val snippet: String, val position: LatLng)

/**
 * Maps an external [Place] domain model into a display-ready [PlaceItemUiModel].
 *
 * The mapper encapsulates all data normalization, default value fallbacks (such as fallback
 * titles), and string formatting (such as appending third-party attributions to the address).
 * Keeping this transformation logic in the mapper prevents business and formatting logic
 * from leaking into the UI components. Returns `null` if essential coordinates are missing.
 */
internal fun toPlaceItemUiModel(place: Place, defaultTitle: String): PlaceItemUiModel? {
    val position = place.location ?: return null
    val title = place.displayName ?: defaultTitle
    val snippet = buildString {
        place.formattedAddress?.let { append(it) }
        place.attributions?.takeIf { it.isNotEmpty() }?.let {
            if (isNotEmpty()) append("\n")
            append(it.joinToString("\n"))
        }
    }
    return PlaceItemUiModel(title = title, snippet = snippet, position = position)
}

Configura il progetto di sviluppo

Segui questi passaggi per creare il progetto del tutorial in Android Studio.

  1. Scarica e installa Android Studio.
  2. Aggiungi il pacchetto Google Play Services ad Android Studio.
  3. Clona o scarica il repository di esempi v2 dell'API Google Maps Android se non l'hai fatto quando hai iniziato a leggere questo tutorial.

  4. Importa il progetto del tutorial:

    • In Android Studio, seleziona File > Nuovo > Importa progetto.
    • Vai alla posizione in cui hai salvato il repository di esempio v2 dell'API Google Maps Android dopo averlo scaricato.
    • Trova il progetto CurrentPlaceDetailsOnMap in questa posizione:
      PATH-TO-SAVED-REPO/android-samples/tutorials/java/CurrentPlaceDetailsOnMap (Java) o
      PATH-TO-SAVED-REPO/android-samples/tutorials/kotlin/CurrentPlaceDetailsOnMap (Kotlin)
    • Seleziona la directory del progetto, quindi fai clic su Apri. Android Studio ora crea il progetto utilizzando lo strumento di build Gradle.

Abilita le API necessarie e ottieni una chiave API

Per completare questo tutorial, devi avere un progetto Google Cloud con le API necessarie abilitate e una chiave API autorizzata a utilizzare Maps SDK for Android. Per ulteriori dettagli, vedi:

Per visualizzare le API abilitate, vai alla pagina di Google Maps Platform nella console Cloud e seleziona il tuo progetto:

Vai alla pagina di Google Maps Platform

Se l'API Places non è abilitata nel tuo progetto, devi abilitarla:

Abilita l'API Places

Se aggiungi limitazioni alla chiave API, assicurati di aggiungere l'API Places alla chiave. Per saperne di più, consulta Utilizzo delle chiavi API.

Aggiungi la chiave API all'app

  1. Apri il file local.properties del progetto.

  2. Aggiungi la seguente stringa e poi sostituisci YOUR_API_KEY con il valore della tua chiave API:

    MAPS_API_KEY=YOUR_API_KEY

    Quando crei l'app, il plug-in Secrets Gradle per Android copia la chiave API e la rende disponibile come variabile di compilazione nel manifest Android.

Crea ed esegui la tua app

  1. Collega un dispositivo Android al computer. Segui le istruzioni per attivare le Opzioni sviluppatore sul tuo dispositivo Android e configurare il sistema in modo che rilevi il dispositivo.

    In alternativa, puoi utilizzare Gestione Android Virtual Device (AVD) per configurare un dispositivo virtuale. Quando scegli un emulatore, assicurati di selezionare un'immagine che includa le API di Google. Per maggiori dettagli, consulta la sezione Configura un progetto Android Studio.

  2. In Android Studio, fai clic sull'opzione di menu Esegui (o sull'icona del pulsante di riproduzione). Scegli un dispositivo come richiesto.

Android Studio richiama Gradle per creare l'app, quindi la esegue sul dispositivo o sull'emulatore. Dovresti visualizzare una mappa con un numero di indicatori centrati intorno alla tua posizione attuale, simile all'immagine in questa pagina.

  1. Seleziona Ottieni luogo per aprire un elenco di luoghi (un'attività o un altro punto d'interesse) vicino alla tua posizione attuale. Per visualizzare l'elenco dei luoghi, devi concedere l'autorizzazione di accesso alla posizione quando richiesto.
  2. Seleziona un luogo dall'elenco. Sulla mappa viene aggiunto un indicatore per il luogo selezionato.

Risoluzione dei problemi:

  • Se non vedi una mappa, verifica di aver ottenuto una chiave API e di averla aggiunta all'app, come descritto sopra. Controlla il log in Android Monitor di Android Studio per verificare la presenza di messaggi di errore relativi alla chiave API.
  • Se la mappa mostra un solo indicatore situato sul Sydney Harbour Bridge (la località predefinita specificata nell'app), verifica di aver concesso l'autorizzazione di accesso alla posizione all'app. L'app richiede l'autorizzazione di accesso alla posizione in fase di runtime, seguendo il pattern descritto nella guida alle autorizzazioni Android. Tieni presente che puoi anche impostare le autorizzazioni direttamente sul dispositivo, scegliendo Impostazioni > App > nome app > Autorizzazioni > Posizione. Per informazioni dettagliate su come gestire le autorizzazioni nel tuo codice, consulta la guida di seguito per richiedere l'autorizzazione di accesso alla posizione nella tua app.
  • Utilizza gli strumenti di debug di Android Studio per visualizzare i log ed eseguire il debug dell'app.

comprendi il codice

Questa parte del tutorial spiega le parti più significative dell'app CurrentPlaceDetailsOnMap per aiutarti a capire come creare un'app simile.

Crea un'istanza del client API Places

Questi oggetti sono i punti di accesso principali a Places SDK for Android:

  • La classe Places crea e gestisce i client per Places SDK for Android.
  • L'interfaccia PlacesClient recupera la posizione corrente del dispositivo e i luoghi nelle vicinanze.

L'interfaccia LocationServices è l'entry point principale per i servizi di localizzazione di Android.

Per utilizzare le API, procedi come segue nel metodo onCreate() del tuo frammento o della tua attività:

  1. Inizializza un oggetto Places.
  2. Crea un oggetto PlacesClient.
  3. Crea un oggetto FusedLocationProviderClient.

Ad esempio:

Java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // ...

    // Retrieve the content view that renders the map.
    setContentView(R.layout.activity_maps);

    // Construct a PlacesClient
    Places.initialize(getApplicationContext(), getString(R.string.maps_api_key));
    placesClient = Places.createClient(this);

    // Construct a FusedLocationProviderClient.
    fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
}

Kotlin

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    // ...

    // Retrieve the content view that renders the map.
    setContentView(R.layout.activity_maps)

    // Construct a PlacesClient
    Places.initialize(applicationContext, getString(R.string.maps_api_key))
    placesClient = Places.createClient(this)

    // Construct a FusedLocationProviderClient.
    fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this)

}

Richiedi autorizzazione di accesso alla posizione

La tua app deve richiedere l'autorizzazione di accesso alla posizione per determinare la posizione del dispositivo e consentire all'utente di toccare il pulsante La mia posizione sulla mappa.

Questo tutorial fornisce il codice necessario per richiedere l'autorizzazione di accesso alla posizione esatta. Per maggiori dettagli, consulta la guida alle autorizzazioni Android.

  1. Aggiungi l'autorizzazione come elemento secondario dell'elemento <manifest> nel manifest Android:

    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.currentplacedetailsonmap">
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
</manifest>

  2. Richiedi le autorizzazioni di runtime nella tua app, dando all'utente la possibilità di consentire o negare l'autorizzazione di accesso alla posizione. Il seguente codice controlla se l'utente ha concesso l'autorizzazione di accesso alla posizione esatta. In caso contrario, richiede l'autorizzazione:

    Java

    private void getLocationPermission() {
    /*
     * Request location permission, so that we can get the location of the
     * device. The result of the permission request is handled by a callback,
     * onRequestPermissionsResult.
     */
    if (ContextCompat.checkSelfPermission(
                    this.getApplicationContext(),
                    android.Manifest.permission.ACCESS_FINE_LOCATION)
            == PackageManager.PERMISSION_GRANTED) {
        locationPermissionGranted = true;
    } else {
        ActivityCompat.requestPermissions(
                this,
                new String[] {android.Manifest.permission.ACCESS_FINE_LOCATION},
                PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
    }
}

    Kotlin

    private fun getLocationPermission() {
    /*
     * Request location permission, so that we can get the location of the
     * device. The result of the permission request is handled by a callback,
     * onRequestPermissionsResult.
     */
    if (ContextCompat.checkSelfPermission(
            this.applicationContext,
            Manifest.permission.ACCESS_FINE_LOCATION,
        )
        == PackageManager.PERMISSION_GRANTED
    ) {
        locationPermissionGranted = true
    } else {
        ActivityCompat.requestPermissions(
            this,
            arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
            PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION,
        )
    }
}

  3. Esegui l'override del callback onRequestPermissionsResult() per gestire il risultato della richiesta di autorizzazione:

    Java

    @Override
public void onRequestPermissionsResult(
        int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    locationPermissionGranted = false;
    if (requestCode
            == PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION) { // If request is cancelled, the
        // result arrays are empty.
        if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            locationPermissionGranted = true;
        }
    } else {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }
    updateLocationUI();
}

    Kotlin

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
    locationPermissionGranted = false
    when (requestCode) {
        PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION -> {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.isNotEmpty() &&
                grantResults[0] == PackageManager.PERMISSION_GRANTED
            ) {
                locationPermissionGranted = true
            }
        }

        else -> super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    }
    updateLocationUI()
}

    Una sezione successiva di questo tutorial descrive il metodo updateLocationUI().

Aggiungi una mappa

Visualizzare una mappa utilizzando Maps SDK for Android.

  1. Aggiungi un elemento <fragment> al file di layout dell'attività, activity_maps.xml. Questo elemento definisce un SupportMapFragment che funge da contenitore per la mappa e fornisce l'accesso all'oggetto GoogleMap. Il tutorial utilizza la versione del frammento di mappa della libreria Android Support Library per garantire la compatibilità con le versioni precedenti del framework Android.

    <!--
 Copyright 2020 Google LLC

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/map"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.currentplacedetailsonmap.MapsActivityCurrentPlace" />

  2. Nel metodo onCreate() della tua attività, imposta il file di layout come visualizzazione dei contenuti:

    Java

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    // Retrieve the content view that renders the map.
    setContentView(R.layout.activity_maps);

}

    Kotlin

    override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)


    // Retrieve the content view that renders the map.
    setContentView(R.layout.activity_maps)

}

  3. Implementa l'interfaccia OnMapReadyCallback ed esegui l'override del metodo onMapReady() per configurare la mappa quando l'oggetto GoogleMap è disponibile:

    Java

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

    // ...

    // Turn on the My Location layer and the related control on the map.
    updateLocationUI();

    // Get the current location of the device and set the position of the map.
    getDeviceLocation();
}

    Kotlin

    override fun onMapReady(map: GoogleMap) {
    this.map = map

    // ...

    // Turn on the My Location layer and the related control on the map.
    updateLocationUI()

    // Get the current location of the device and set the position of the map.
    getDeviceLocation()
}

  4. Nel metodo onCreate() della tua attività, ottieni un handle per il frammento di mappa chiamando FragmentManager.findFragmentById(). Quindi utilizza getMapAsync() per registrarti al callback della mappa:

    Java

    SupportMapFragment mapFragment =
        (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);

    Kotlin

    val mapFragment = supportFragmentManager
    .findFragmentById(R.id.map) as SupportMapFragment?
mapFragment?.getMapAsync(this)

  5. Scrivi un metodo updateLocationUI() per impostare i controlli della posizione sulla mappa. Se l'utente ha concesso l'autorizzazione di accesso alla posizione, attiva il livello La mia posizione e il relativo controllo sulla mappa, altrimenti disattiva il livello e il controllo e imposta la posizione corrente su null:

    Java

    private void updateLocationUI() {
    if (map == null) {
        return;
    }
    try {
        if (locationPermissionGranted) {
            map.setMyLocationEnabled(true);
            map.getUiSettings().setMyLocationButtonEnabled(true);
        } else {
            map.setMyLocationEnabled(false);
            map.getUiSettings().setMyLocationButtonEnabled(false);
            lastKnownLocation = null;
        }
    } catch (SecurityException e) {
        Log.e("Exception: %s", e.getMessage());
    }
}

    Kotlin

    @SuppressLint("MissingPermission")
private fun updateLocationUI() {
    if (map == null) {
        return
    }
    try {
        if (locationPermissionGranted) {
            map?.isMyLocationEnabled = true
            map?.uiSettings?.isMyLocationButtonEnabled = true
        } else {
            map?.isMyLocationEnabled = false
            map?.uiSettings?.isMyLocationButtonEnabled = false
            lastKnownLocation = null
            getLocationPermission()
        }
    } catch (e: SecurityException) {
        Log.e("Exception: %s", e.message, e)
    }
}

Recupera la posizione del dispositivo Android e posiziona la mappa

Utilizza il provider di geolocalizzazione integrata per trovare l'ultima posizione nota del dispositivo, quindi utilizza questa posizione per posizionare la mappa. Il tutorial fornisce il codice necessario. Per maggiori dettagli su come ottenere la posizione del dispositivo, consulta la guida al provider di geolocalizzazione combinata nelle API di geolocalizzazione di Google Play Services.

Java

private void getDeviceLocation() {
    /*
     * Get the best and most recent location of the device, which may be null in rare
     * cases when a location is not available.
     */
    try {
        if (locationPermissionGranted) {
            Task<Location> locationResult = fusedLocationProviderClient.getLastLocation();
            locationResult.addOnCompleteListener(
                    this,
                    new OnCompleteListener<Location>() {
                        @Override
                        public void onComplete(@NonNull Task<Location> task) {
                            if (task.isSuccessful()) {
                                // Set the map's camera position to the current location of the
                                // device.
                                lastKnownLocation = task.getResult();
                                if (lastKnownLocation != null) {
                                    map.moveCamera(
                                            CameraUpdateFactory.newLatLngZoom(
                                                    new LatLng(
                                                            lastKnownLocation.getLatitude(),
                                                            lastKnownLocation.getLongitude()),
                                                    DEFAULT_ZOOM));
                                }
                            } else {
                                Log.d(TAG, "Current location is null. Using defaults.");
                                Log.e(TAG, "Exception: %s", task.getException());
                                map.moveCamera(
                                        CameraUpdateFactory.newLatLngZoom(
                                                defaultLocation, DEFAULT_ZOOM));
                                map.getUiSettings().setMyLocationButtonEnabled(false);
                            }
                        }
                    });
        }
    } catch (SecurityException e) {
        Log.e("Exception: %s", e.getMessage(), e);
    }
}

Kotlin

@SuppressLint("MissingPermission")
private fun getDeviceLocation() {
    /*
     * Get the best and most recent location of the device, which may be null in rare
     * cases when a location is not available.
     */
    try {
        if (locationPermissionGranted) {
            val locationResult = fusedLocationProviderClient.lastLocation
            locationResult.addOnCompleteListener(this) { task ->
                if (task.isSuccessful) {
                    // Set the map's camera position to the current location of the device.
                    lastKnownLocation = task.result
                    if (lastKnownLocation != null) {
                        map?.moveCamera(
                            CameraUpdateFactory.newLatLngZoom(
                                LatLng(
                                    lastKnownLocation!!.latitude,
                                    lastKnownLocation!!.longitude,
                                ),
                                DEFAULT_ZOOM.toFloat(),
                            ),
                        )
                    }
                } else {
                    Log.d(TAG, "Current location is null. Using defaults.")
                    Log.e(TAG, "Exception: %s", task.exception)
                    map?.moveCamera(
                        CameraUpdateFactory
                            .newLatLngZoom(defaultLocation, DEFAULT_ZOOM.toFloat()),
                    )
                    map?.uiSettings?.isMyLocationButtonEnabled = false
                }
            }
        }
    } catch (e: SecurityException) {
        Log.e("Exception: %s", e.message, e)
    }
}

Ottieni il luogo attuale

Utilizza Places SDK for Android per ottenere un elenco di luoghi probabili nella posizione corrente del dispositivo. In questo contesto, un luogo è un'attività o un altro punto d'interesse.

Questo tutorial recupera il luogo attuale quando l'utente fa clic sul pulsante Recupera luogo. Offre all'utente un elenco di luoghi probabili tra cui scegliere, quindi aggiunge un indicatore sulla mappa nella posizione del luogo selezionato. Il tutorial fornisce il codice necessario per interagire con Places SDK for Android. Per maggiori dettagli, consulta la guida su come ottenere il luogo attuale.

  1. Crea un file di layout (current_place_menu.xml) per il menu opzioni ed esegui l'override del metodo onCreateOptionsMenu() per configurare il menu opzioni. Per il codice, consulta l'app di esempio associata.
  2. Esegui l'override del metodo onOptionsItemSelected() per ottenere il luogo attuale quando l'utente fa clic sull'opzione Ottieni luogo:

    Java

    @Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId() == R.id.option_get_place) {
        showCurrentPlace();
    }
    return true;
}

    Kotlin

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
    if (item.itemId == R.id.option_get_place) {
        showCurrentPlace()
    }
    return true
}

  3. Crea un metodo showCurrentPlace() per ottenere un elenco di luoghi probabili nella posizione corrente del dispositivo:

    Java

    private void showCurrentPlace() {
    if (map == null) {
        return;
    }

    // ...

    if (locationPermissionGranted) {
        // Use fields to define the data types to return.
        List<Place.Field> placeFields =
                Arrays.asList(
                        Place.Field.DISPLAY_NAME,
                        Place.Field.FORMATTED_ADDRESS,
                        Place.Field.LOCATION);

        // Search around the device's last-known location, falling back to the center of the
        // map if the location is not available yet.
        LatLng center =
                lastKnownLocation != null
                        ? new LatLng(
                                lastKnownLocation.getLatitude(),
                                lastKnownLocation.getLongitude())
                        : map.getCameraPosition().target;
        CircularBounds searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS);

        // Use the builder to create a SearchNearbyRequest that returns the closest places
        // first.
        SearchNearbyRequest request =
                SearchNearbyRequest.builder(searchArea, placeFields)
                        .setMaxResultCount(M_MAX_ENTRIES)
                        .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE)
                        .build();

        // Get the likely places - that is, the businesses and other points of interest that
        // are closest to the device's current location.
        final Task<SearchNearbyResponse> placeResult = placesClient.searchNearby(request);
        placeResult.addOnCompleteListener(
                new OnCompleteListener<SearchNearbyResponse>() {
                    @Override
                    public void onComplete(@NonNull Task<SearchNearbyResponse> task) {
                        if (task.isSuccessful() && task.getResult() != null) {
                            List<Place> responsePlaces = task.getResult().getPlaces();
                            int count = Math.min(responsePlaces.size(), M_MAX_ENTRIES);
                            List<PlaceItemUiModel> likelyPlaces = new ArrayList<>();
                            for (int i = 0; i < count; i++) {
                                PlaceItemUiModel model = toUiModel(responsePlaces.get(i));
                                if (model != null) {
                                    likelyPlaces.add(model);
                                }
                            }

                            // Show a dialog offering the user the list of likely places, and
                            // add a marker at the selected place.
                            MapsActivityCurrentPlace.this.openPlacesDialog(likelyPlaces);
                        } else {
                            Log.e(TAG, "Exception: %s", task.getException());
                        }
                    }
                });
    } else {
        // The user has not granted permission.
        Log.i(TAG, "The user did not grant location permission.");

        // Add a default marker, because the user hasn't selected a place.
        map.addMarker(
                new MarkerOptions()
                        .title(getString(R.string.default_info_title))
                        .position(defaultLocation)
                        .snippet(getString(R.string.default_info_snippet)));

        // Prompt the user for permission.
        getLocationPermission();
    }
}

    Kotlin

    private fun showCurrentPlace() {
    val map = map ?: return
    // ...
    if (locationPermissionGranted) {
        // Use fields to define the data types to return.
        val placeFields = listOf(
            Place.Field.DISPLAY_NAME,
            Place.Field.FORMATTED_ADDRESS,
            Place.Field.LOCATION,
        )

        // Search around the device's last-known location, falling back to the center of
        // the map if the location is not available yet.
        val center = lastKnownLocation?.let { LatLng(it.latitude, it.longitude) }
            ?: map.cameraPosition.target
        val searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS)

        // Use the builder to create a SearchNearbyRequest that returns the closest places
        // first.
        val request = SearchNearbyRequest.builder(searchArea, placeFields)
            .setMaxResultCount(M_MAX_ENTRIES)
            .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE)
            .build()

        // Get the likely places - that is, the businesses and other points of interest that
        // are closest to the device's current location.
        val placeResult = placesClient.searchNearby(request)
        placeResult.addOnCompleteListener { task ->
            if (task.isSuccessful && task.result != null) {
                val likelyPlaces = task.result.places
                    .take(M_MAX_ENTRIES)
                    .mapNotNull { it.toUiModel() }

                // Show a dialog offering the user the list of likely places, and add a
                // marker at the selected place.
                openPlacesDialog(likelyPlaces)
            } else {
                Log.e(TAG, "Exception: %s", task.exception)
            }
        }
    } else {
        // The user has not granted permission.
        Log.i(TAG, "The user did not grant location permission.")

        // Add a default marker, because the user hasn't selected a place.
        map.addMarker(
            MarkerOptions()
                .title(getString(R.string.default_info_title))
                .position(defaultLocation)
                .snippet(getString(R.string.default_info_snippet)),
        )

        // Prompt the user for permission.
        getLocationPermission()
    }
}

  4. Crea un metodo openPlacesDialog() per visualizzare un modulo che consenta all'utente di selezionare un luogo da un elenco di luoghi probabili. Aggiungi un indicatore sulla mappa per il luogo selezionato. I contenuti dell'indicatore includono il nome e l'indirizzo del luogo, nonché eventuali attribuzioni fornite dall'API:

    Java

    void openPlacesDialog(List<PlaceItemUiModel> likelyPlaces) {
    // ...
    // Ask the user to choose the place where they are now.
    DialogInterface.OnClickListener listener =
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // The "which" argument contains the position of the selected item.
                    PlaceItemUiModel selectedPlace = likelyPlaces.get(which);

                    // Add a marker for the selected place, with an info window
                    // showing information about that place.
                    map.addMarker(
                            new MarkerOptions()
                                    .title(selectedPlace.title)
                                    .position(selectedPlace.position)
                                    .snippet(selectedPlace.snippet));

                    // Position the map's camera at the location of the marker.
                    map.moveCamera(
                            CameraUpdateFactory.newLatLngZoom(
                                    selectedPlace.position, DEFAULT_ZOOM));
                }
            };

    // Display the dialog.
    String[] titles = new String[likelyPlaces.size()];
    for (int i = 0; i < likelyPlaces.size(); i++) {
        titles[i] = likelyPlaces.get(i).title;
    }
    new AlertDialog.Builder(this)
            .setTitle(R.string.pick_place)
            .setItems(titles, listener)
            .show();
}

    Kotlin

    internal fun openPlacesDialog(likelyPlaces: List<PlaceItemUiModel>) {
    // ...
    // Ask the user to choose the place where they are now.
    val listener = DialogInterface.OnClickListener { _, which ->
        // The "which" argument contains the position of the selected item.
        val selectedPlace = likelyPlaces[which]

        // Add a marker for the selected place, with an info window
        // showing information about that place.
        selectedMarker = map?.addMarker(
            MarkerOptions()
                .title(selectedPlace.title)
                .position(selectedPlace.position)
                .snippet(selectedPlace.snippet),
        )

        // Position the map's camera at the location of the marker.
        map?.moveCamera(
            CameraUpdateFactory.newLatLngZoom(
                selectedPlace.position,
                DEFAULT_ZOOM.toFloat(),
            ),
        )
    }

    // Display the dialog.
    val titles = likelyPlaces.map { it.title }.toTypedArray()
    AlertDialog.Builder(this)
        .setTitle(R.string.pick_place)
        .setItems(titles, listener)
        .show()
}

  5. Crea un layout personalizzato per i contenuti della finestra informativa. In questo modo è possibile visualizzare più righe di contenuti nella finestra informativa. Innanzitutto, aggiungi un file di layout XML, custom_info_contents.xml, contenente una visualizzazione di testo per il titolo della finestra informativa e un'altra visualizzazione di testo per lo snippet (ovvero i contenuti testuali della finestra informativa):

    <?xml version="1.0" encoding="utf-8"?>
<!--
 Copyright 2020 Google LLC

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layoutDirection="locale"
    android:orientation="vertical">
    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:textColor="#ff000000"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/snippet"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#ff7f7f7f" />
</LinearLayout>

  6. Implementa l'interfaccia InfoWindowAdapter per espandere il layout e caricare i contenuti della finestra informativa:

    Java

    // Use a custom info window adapter to handle multiple lines of text in the
// info window contents.
this.map.setInfoWindowAdapter(
        new GoogleMap.InfoWindowAdapter() {

            @Override
            // Return null here, so that getInfoContents() is called next.
            public View getInfoWindow(Marker arg0) {
                return null;
            }

            @Override
            public View getInfoContents(Marker marker) {
                // Inflate the layouts for the info window, title and snippet.
                View infoWindow =
                        getLayoutInflater()
                                .inflate(
                                        R.layout.custom_info_contents,
                                        (FrameLayout) findViewById(R.id.map),
                                        false);

                TextView title = infoWindow.findViewById(R.id.title);
                title.setText(marker.getTitle());

                TextView snippet = infoWindow.findViewById(R.id.snippet);
                snippet.setText(marker.getSnippet());

                return infoWindow;
            }
        });

    Kotlin

    // Use a custom info window adapter to handle multiple lines of text in the
// info window contents.
this.map?.setInfoWindowAdapter(object : InfoWindowAdapter {
    // Return null here, so that getInfoContents() is called next.
    override fun getInfoWindow(arg0: Marker): View? = null

    override fun getInfoContents(marker: Marker): View {
        // Inflate the layouts for the info window, title and snippet.
        val infoWindow = layoutInflater.inflate(
            R.layout.custom_info_contents,
            findViewById<FrameLayout>(R.id.map),
            false,
        )
        val title = infoWindow.findViewById<TextView>(R.id.title)
        title.text = marker.title
        val snippet = infoWindow.findViewById<TextView>(R.id.snippet)
        snippet.text = marker.snippet
        return infoWindow
    }
})

Salva lo stato della mappa

Salva la posizione della videocamera della mappa e la posizione del dispositivo. Quando un utente ruota un dispositivo Android o apporta modifiche alla configurazione, il framework Android distrugge e ricrea l'attività su Maps. Per garantire un'esperienza utente fluida, è consigliabile archiviare lo stato dell'applicazione pertinente e ripristinarlo quando necessario.

Questo tutorial fornisce tutto il codice necessario per salvare lo stato della mappa. Per maggiori dettagli, consulta la guida al bundle savedInstanceState.

  1. Nell'attività su Maps, configura le coppie chiave-valore per memorizzare lo stato dell'attività:

    Java

    private static final String KEY_CAMERA_POSITION = "camera_position";
private static final String KEY_LOCATION = "location";

    Kotlin

    private const val KEY_CAMERA_POSITION = "camera_position"
private const val KEY_LOCATION = "location"

  2. Implementa il callback onSaveInstanceState() per salvare lo stato quando l'attività viene messa in pausa:

    Java

    @Override
protected void onSaveInstanceState(Bundle outState) {
    if (map != null) {
        outState.putParcelable(KEY_CAMERA_POSITION, map.getCameraPosition());
        outState.putParcelable(KEY_LOCATION, lastKnownLocation);
    }
    super.onSaveInstanceState(outState);
}

    Kotlin

    override fun onSaveInstanceState(outState: Bundle) {
    map?.let { map ->
        outState.putParcelable(KEY_CAMERA_POSITION, map.cameraPosition)
        outState.putParcelable(KEY_LOCATION, lastKnownLocation)
    }
    super.onSaveInstanceState(outState)
}

  3. Nel metodo onCreate() della tua attività, recupera la posizione del dispositivo e la posizione della fotocamera della mappa, se salvate in precedenza:

    Java

    // Retrieve location and camera position from saved instance state.
if (savedInstanceState != null) {
    lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION);
    cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION);
}

    Kotlin

    if (savedInstanceState != null) {
    lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION)
    cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION)
}