参数类型'LatLng‘不能分配给参数类型'LatLng?’

Question

当在MapOptions-> Center中使用地图时，当输入lat和液化天然气时，参数类型'LatLng‘不能分配给参数类型'LatLng?’。

class MapsView extends HookConsumerWidget {
  MapsView({Key? key}) : super(key: key);
   final MapController _mapController=MapController();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return FlutterMap(
      options: MapOptions(
       center: LatLng(51.509364, -0.128928),
        zoom: 9.2,
      ),
      layers: [
        TileLayerOptions(
          urlTemplate: "https://tile.openstreetmap.org/{z}/{x}/{y}.png",
          userAgentPackageName: 'com.example.app',
        ),
      ],
      nonRotatedChildren: [
        AttributionWidget.defaultWidget(
          source: 'OpenStreetMap contributors',
          onSourceTapped: null,
        ),
      ],
    );
  }

  }

​

​

Answer 1

import 'package:latlong2/latlong.dart';
import 'package:flutter_map/flutter_map.dart';
 class MapsView extends HookConsumerWidget {
  MapsView({Key? key}) : super(key: key);
 final MapController _mapController=MapController();

 @override
  Widget build(BuildContext context, WidgetRef ref) {
return FlutterMap(
  options: MapOptions(
   center: LatLng(51.509364, -0.128928),
    zoom: 9.2,
  ),
  layers: [
    TileLayerOptions(
      urlTemplate: "https://tile.openstreetmap.org/{z}/{x}/{y}.png",
      userAgentPackageName: 'com.example.app',
    ),
  ],
  nonRotatedChildren: [
    AttributionWidget.defaultWidget(
      source: 'OpenStreetMap contributors',
      onSourceTapped: null,
    ),
  ],
);
}

 }

'package:latlong2/latlong.dart导入

在包中没有导出，所以您必须手动导入它才能在其中赋值。

​

Answer 2

我认为你不需要使用latLng2

依赖关系: latlong2：^0.8.0

import 'package:latlong2/latlong.dart' as latLng;

FlutterMap(
      options: MapOptions(
       center: latLng.LatLng(51.509364, -0.128928),
        zoom: 9.2,
      ),