我试图通过长按位置并显示位置名称来在谷歌地图上添加标记，但是，每当我长按时，标记都会出现一瞬间，然后消失。
我知道长按后标记应该保留，然后也显示标题，，但这不起作用。
请告诉我，如果有人面临任何这样的问题，可以帮助我解决。
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, GoogleMap.OnMapLongClickListener {
private GoogleMap mMap;
LocationManager locationManager;
LocationListener locationListener;
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (grantResults.length>0 && grantResults[0]==PackageManager.PERMISSION_GRANTED){
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)==PackageManager.PERMISSION_GRANTED){
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
Location lastKnownLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
centerMapOnLocation(lastKnownLocation, "Your Location");
}
}
}
public void centerMapOnLocation(Location location, String title) {
LatLng userLocation = new LatLng(location.getLatitude(), location.getLongitude());
mMap.clear();
if (title != "Your Location"){
mMap.addMarker(new MarkerOptions().position(userLocation).title(title));
}
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(userLocation, 10));
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.setOnMapLongClickListener(this);
Intent intent = getIntent();
if (intent.getIntExtra("placeNumber", 0) == 0) {
//zoom in on the user's location
locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
locationListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
centerMapOnLocation(location, "Your Location");
}
@Override
public void onStatusChanged(String s, int i, Bundle bundle) {
}
@Override
public void onProviderEnabled(String s) {
}
@Override
public void onProviderDisabled(String s) {
}
};
if (Build.VERSION.SDK_INT < 23) {
if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// Activity#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for Activity#requestPermissions for more details.
return;
}
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
} else {
if(ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)==PackageManager.PERMISSION_GRANTED){
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
Location lastKnownLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
centerMapOnLocation(lastKnownLocation, "Your Location");
} else {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},1);
}
}
}
}
@Override
public void onMapLongClick(LatLng latLng) {
Geocoder geocoder = new Geocoder(getApplicationContext(), Locale.getDefault());
String address ="";
try {
List <Address> listAddresses= geocoder.getFromLocation(latLng.latitude,latLng.longitude,1);
if (listAddresses!=null&& listAddresses.size()>0){
if (listAddresses.get(0).getThoroughfare()!=null){
if (listAddresses.get(0).getSubThoroughfare()!=null){
address+=listAddresses.get(0).getSubThoroughfare()+" ";
}
address+= listAddresses.get(0).getThoroughfare();
}
}
} catch (IOException e) {
e.printStackTrace();
}
if (address == ""){
SimpleDateFormat sdf = new SimpleDateFormat("mm:HH yyyyMMdd", Locale.getDefault());
address = sdf.format(new Date());
}
mMap.addMarker(new MarkerOptions().position(latLng).title(address).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA)));
}
}
每次您的位置在这里更改时，您都会清除您的地图：
@Override
public void onLocationChanged(Location location) {
centerMapOnLocation(location, "Your Location");
}
这就是为什么您的标记在添加到地图后立即消失的原因。如果您在centerMapOnLocation方法中删除或注释掉这一行：
mMap.clear();
然后标记不再消失。
希望这能有所帮助！