class - 如何在 flutter (dart) 中访问其他类的方法？

Question

我在脚手架中使用了 flutter map，并且在脚手架小部件类中有一个名为“showMyBottomSheet”的方法。当点击 map 并打开底部工作表时，用于执行此方法的 map 。

但现在我已将这两个文件分开，我无法从 map 类访问脚手架有状态小部件中的“showMyBottomSheet”方法。

我该怎么做？我不应该把它们分开吗？

我的主页 - home.dart

class MyHomePage extends StatefulWidget {
  static const String route = '/';

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static const String route = '/';

  // Bottom sheet
  final _scaffoldKey = new GlobalKey<ScaffoldState>();

  dynamic showMyBottomSheet(LatLng latlang) {
    _scaffoldKey.currentState.showBottomSheet((context) {
      return new CustomBottomSheet();
    });
  }

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      key: _scaffoldKey,
      drawer: buildDrawer(context, route),
      body: new Column(
        children: [
          new CustomMap(),
        ],
      ),
    );
  }
}

map 小部件 - flutterMap.dart

class Cuenter code herestomMap extends StatefulWidget {
  @override
  _CustomMapState createState() => new _CustomMapState();
}

class _CustomMapState extends State<CustomMap> {
  var markers = <Marker>[];

  @override
  Widget build(BuildContext context) {
    return new Flexible(
      child: new FlutterMap(
        options: new MapOptions(
            center: new LatLng(51.25, 30.5),
            zoom: 15.0,
            onTap: // I want to call showMyBottomSheet method (from home page) here
        ),
        layers: [
          new TileLayerOptions(
              urlTemplate:
              "https://maps.wikimedia.org/osm-intl/{z}/{x}/{y}.png",
              subdomains: ['a', 'b', 'c']),
        ],
      ),
    );
  }
}

Answer 1

首先，请注意，任何以下划线开头的方法在 Dart 中都将被视为私有(private)方法。 look here .

在这种情况下，您应该将该方法传递给子部件并在稍后调用它。检查这个例子:

class MyHomePage extends StatefulWidget {
  static const String route = '/';

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static const String route = '/';

  // Bottom sheet
  final _scaffoldKey = new GlobalKey<ScaffoldState>();

  dynamic showMyBottomSheet(LatLng latlang) {
    _scaffoldKey.currentState.showBottomSheet((context) {
      return new CustomBottomSheet();
    });
  }

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      key: _scaffoldKey,
      drawer: buildDrawer(context, route),
      body: new Column(
        children: [
          new CustomMap(onMapTap: showMyBottomSheet),
        ],
      ),
    );
  }
}

在 flutterMap.dart 中:

class CustomMap extends StatefulWidget {
  Function onMapTap;
  CustomMap({this.onMapTap});

  @override
  _CustomMapState createState() => new _CustomMapState();
}

class _CustomMapState extends State<CustomMap> {
  var markers = <Marker>[];

  @override
  Widget build(BuildContext context) {
    return new Flexible(
      child: new FlutterMap(
        options: new MapOptions(
            center: new LatLng(51.25, 30.5),
            zoom: 15.0,
            onTap: (){
              widget.onMapTap(LatLng(34.12312,56.1323));
            }
        ),
        layers: [
          new TileLayerOptions(
              urlTemplate:
              "https://maps.wikimedia.org/osm-intl/{z}/{x}/{y}.png",
              subdomains: ['a', 'b', 'c']),
        ],
      ),
    );
  }
}