我的代码有问题，它应该显示当前位置的纬度和经度。我曾尝试简单地在 TextView 对象中设置文本，不幸的是，它只显示一次（在开始时）提到的值。我想问您如何更改此行为以进行“实时”坐标更新。
这是我的代码
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.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
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 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.Place;
import com.google.android.libraries.places.api.model.PlaceLikelihood;
import com.google.android.libraries.places.api.net.FindCurrentPlaceRequest;
import com.google.android.libraries.places.api.net.FindCurrentPlaceResponse;
import com.google.android.libraries.places.api.net.PlacesClient;
import org.w3c.dom.Text;
import java.util.Arrays;
import java.util.List;
import static com.example.currentplacedetailsonmap.R.id.coordinates;
/**
* 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;
// 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.
private Location lastKnownLocation;
// Keys for storing activity state.
// [START maps_current_place_state_keys]
private static final String KEY_CAMERA_POSITION = "camera_position";
private static final String KEY_LOCATION = "location";
// [END maps_current_place_state_keys]
// Used for selecting the current place.
private static final int M_MAX_ENTRIES = 5;
private String[] likelyPlaceNames;
private String[] likelyPlaceAddresses;
private List[] likelyPlaceAttributions;
private LatLng[] likelyPlaceLatLngs;
// [START maps_current_place_on_create]
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// [START_EXCLUDE silent]
// [START maps_current_place_on_create_save_instance_state]
// Retrieve location and camera position from saved instance state.
if (savedInstanceState != null) {
lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION);
}
// [END maps_current_place_on_create_save_instance_state]
// [END_EXCLUDE]
// Retrieve the content view that renders the map.
setContentView(R.layout.activity_maps);
// [START_EXCLUDE silent]
// Construct a PlacesClient
Places.initialize(getapplicationContext(),BuildConfig.MAPS_API_KEY);
placesClient = Places.createclient(this);
// Construct a FusedLocationProviderClient.
fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
// Build the map.
// [START maps_current_place_map_fragment]
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
// [END maps_current_place_map_fragment]
// [END_EXCLUDE]
}
// [END maps_current_place_on_create]
/**
* Saves the state of the map when the activity is paused.
*/
// [START maps_current_place_on_save_instance_state]
@Override
protected void onSaveInstanceState(Bundle outState) {
if (map != null) {
outState.putParcelable(KEY_CAMERA_POSITION,map.getcameraPosition());
outState.putParcelable(KEY_LOCATION,lastKnownLocation);
}
super.onSaveInstanceState(outState);
}
// [END maps_current_place_on_save_instance_state]
/**
* 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.
*/
// [START maps_current_place_on_options_item_selected]
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.option_get_place) {
showCurrentPlace();
}
return true;
}
// [END maps_current_place_on_options_item_selected]
/**
* Manipulates the map when it's available.
* This callback is triggered when the map is ready to be used.
*/
// [START maps_current_place_on_map_ready]
@Override
public void onmapReady(GoogleMap map) {
this.map = map;
// [START_EXCLUDE]
// [START map_current_place_set_info_window_adapter]
// 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;
}
});
// [END map_current_place_set_info_window_adapter]
// Prompt the user for permission.
getLocationPermission();
// [END_EXCLUDE]
// 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();
}
// [END maps_current_place_on_map_ready]
/**
* Gets the current location of the device,and positions the map's camera.
*/
// [START maps_current_place_get_device_location]
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) {
TextView coordinates = (TextView) findViewById(R.id.coordinates);
LatLng latLng = new LatLng(lastKnownLocation.getLatitude(),lastKnownLocation.getLongitude());
coordinates.setText(latLng.toString());
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);
}
}
// [END maps_current_place_get_device_location]
/**
* Prompts the user for permission to use the device location.
*/
// [START maps_current_place_location_permission]
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);
}
}
// [END maps_current_place_location_permission]
/**
* Handles the result of the request for location permissions.
*/
// [START maps_current_place_on_request_permissions_result]
@Override
public void onRequestPermissionsResult(int requestCode,@NonNull String[] permissions,@NonNull int[] grantResults) {
locationPermissionGranted = false;
switch (requestCode) {
case 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;
}
}
}
updateLocationUI();
}
// [END maps_current_place_on_request_permissions_result]
/**
* 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.
*/
// [START maps_current_place_show_current_place]
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.NAME,Place.Field.ADDRESS,Place.Field.LAT_LNG);
// Use the builder to create a FindCurrentPlaceRequest.
FindCurrentPlaceRequest request =
FindCurrentPlaceRequest.newInstance(placeFields);
// Get the likely places - that is,the businesses and other points of interest that
// are the best match for the device's current location.
@SuppressWarnings("MissingPermission") final
Task<FindCurrentPlaceResponse> placeResult =
placesClient.findCurrentPlace(request);
placeResult.addOnCompleteListener (new OnCompleteListener<FindCurrentPlaceResponse>() {
@Override
public void onComplete(@NonNull Task<FindCurrentPlaceResponse> task) {
if (task.isSuccessful() && task.getResult() != null) {
FindCurrentPlaceResponse likelyPlaces = task.getResult();
// Set the count,handling cases where less than 5 entries are returned.
int count;
if (likelyPlaces.getPlaceLikelihoods().size() < M_MAX_ENTRIES) {
count = likelyPlaces.getPlaceLikelihoods().size();
} else {
count = M_MAX_ENTRIES;
}
int i = 0;
likelyPlaceNames = new String[count];
likelyPlaceAddresses = new String[count];
likelyPlaceAttributions = new List[count];
likelyPlaceLatLngs = new LatLng[count];
for (PlaceLikelihood placeLikelihood : likelyPlaces.getPlaceLikelihoods()) {
// Build a list of likely places to show the user.
likelyPlaceNames[i] = placeLikelihood.getPlace().getName();
likelyPlaceAddresses[i] = placeLikelihood.getPlace().getaddress();
likelyPlaceAttributions[i] = placeLikelihood.getPlace()
.getattributions();
likelyPlaceLatLngs[i] = placeLikelihood.getPlace().getLatLng();
i++;
if (i > (count - 1)) {
break;
}
}
// Show a dialog offering the user the list of likely places,and add a
// marker at the selected place.
MapsactivityCurrentPlace.this.openPlacesDialog();
}
else {
Log.e(TAG,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();
}
}
// [END maps_current_place_show_current_place]
/**
* Displays a form allowing the user to select a place from a list of likely places.
*/
// [START maps_current_place_open_places_dialog]
private void openPlacesDialog() {
// 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.
LatLng markerLatLng = likelyPlaceLatLngs[which];
String markersnippet = likelyPlaceAddresses[which];
if (likelyPlaceAttributions[which] != null) {
markersnippet = markersnippet + "\n" + likelyPlaceAttributions[which];
}
// Add a marker for the selected place,with an info window
// showing information about that place.
map.addMarker(new MarkerOptions()
.title(likelyPlaceNames[which])
.position(markerLatLng)
.snippet(markersnippet));
// Position the map's camera at the location of the marker.
map.moveCamera(CameraUpdateFactory.newLatLngzoom(markerLatLng,DEFAULT_zoom));
}
};
}
// [END maps_current_place_open_places_dialog]
/**
* Updates the map's UI settings based on whether the user has granted location permission.
*/
// [START maps_current_place_update_location_ui]
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;
getLocationPermission();
}
} catch (SecurityException e) {
Log.e("Exception: %s",e.getMessage());
}
}
// [END maps_current_place_update_location_ui]
}
特别是我失败的文本框更新
private void getDeviceLocation() {
/*
* Get the best and most recent location of the device,e);
}
}
预先感谢您的回复。