我已经创建了一个自定义的图像，作为我的标记图标，我的谷歌Map在我的flutter应用程序上。不幸的是，这并没有按计划工作，而是显示默认图标。有人能认出那个人吗？我当然不能。顺便说一句，我的if语句中没有任何内容被打印在控制台中。另一天的问题？
这是我用来设置标记器的代码：

var map;
var rmarker;
final restaurantmarker = BitmapDescriptor.fromAssetImage(
        ImageConfiguration(), 'assets/images/yellow_MarkerR.png')
    .then((value) => rmarker = value);
final mapp = location.getLocation().then((value) => map = value);

final _markers = [
  Marker(
    markerId: MarkerId("my_location"),
    position: LatLng(41.16599, -110.75792),
    infoWindow: InfoWindow(title: "YOUR HOME"),
  ),
  Marker(
      markerId: MarkerId("RESTAURANT"),
      icon: rmarker,
      position: LatLng(40.16599, -110.75792),
      infoWindow: InfoWindow(title: "Restaurant"))
];
final setmarkers = _markers.toSet();

class NearbyScreen extends StatelessWidget {
  void initState() {
    startService();
  }

  @override
  //LocationHelper.mapviewpointer(latitude: )
  Widget build(BuildContext context) {
    return /* !_serviceEnabled ? Center(child:Text("Page cannot be viewed"),) :
        map == null
            ? Center(
                child: Text("Null response"),
              )
            :*/
        GoogleMap(
      initialCameraPosition: CameraPosition(
          target: LatLng(41.16599,
              -110.75792 /*map.latitude, map.longitude
 double.parse(coordinates[0]), double.parse(coordinates[1]) */
              )),
      //minMaxZoomPreference: MinMaxZoomPreference(10, 20),
      zoomControlsEnabled: true,
      markers: setmarkers,
    );
  }
}

这是完整的代码：

Future<bool> assignService(Location loc) async {
  bool servicestatus = await loc.serviceEnabled();
  print("Service status $servicestatus");
  return servicestatus;
}

Future<PermissionStatus> assignPermission(Location loc) async {
  var hasPermission = await loc.hasPermission();
  print("Permission status $hasPermission");
  return hasPermission;
}

Location location = Location();

var _serviceEnabled;
var _serve = assignService(location).then((value) => _serviceEnabled = value);

//var _permissionGranted = assignPermission(location);
var _permissionGranted;
var _permi =
    assignPermission(location).then((value) => _permissionGranted = value);

void startService() {
  if (!_serviceEnabled) {
    _serviceEnabled = assignService(location);
    print("service disabled");
    if (!_serviceEnabled) {
      return;
    }
  }

  if (_permissionGranted == PermissionStatus.denied) {
    _permissionGranted = assignPermission(location);
    print("permission denied");
    if (_permissionGranted != PermissionStatus.granted) {
      return;
    }
  }
}

var map;
var rmarker;
final restaurantmarker = BitmapDescriptor.fromAssetImage(
        ImageConfiguration(), 'assets/images/yellow_MarkerR.png')
    .then((value) => rmarker = value);
final mapp = location.getLocation().then((value) => map = value);

final _markers = [
  Marker(
    markerId: MarkerId("my_location"),
    position: LatLng(41.16599, -110.75792),
    infoWindow: InfoWindow(title: "YOUR HOME"),
  ),
  Marker(
      markerId: MarkerId("RESTAURANT"),
      icon: rmarker,
      position: LatLng(40.16599, -110.75792),
      infoWindow: InfoWindow(title: "Restaurant"))
];
final setmarkers = _markers.toSet();

class NearbyScreen extends StatelessWidget {
  void initState() {
    startService();
  }

  @override
  //LocationHelper.mapviewpointer(latitude: )
  Widget build(BuildContext context) {
    return /* !_serviceEnabled ? Center(child:Text("Page cannot be viewed"),) :
        map == null
            ? Center(
                child: Text("Null response"),
              )
            :*/
        GoogleMap(
      initialCameraPosition: CameraPosition(
          target: LatLng(41.16599,
              -110.75792 /*map.latitude, map.longitude
 double.parse(coordinates[0]), double.parse(coordinates[1]) */
              )),
      //minMaxZoomPreference: MinMaxZoomPreference(10, 20),
      zoomControlsEnabled: true,
      markers: setmarkers,
    );
  }
}

我也在我的终端中得到一个错误，它说：E/包裹（22617）：此处不支持阅读NULL字符串。E/包裹（22617）：此处不支持阅读NULL字符串。