flutter - 'LabeledGlobalKey>'类型不是'GlobalKey 类型的子类型

Question

自Common.dart起，我试图在首页上显示SnackBar，但 flutter 地向我发送如下错误:

通过gesture捕获到异常:

The following assertion was thrown while handling a gesture:
type 'LabeledGlobalKey<State<StatefulWidget>>' is not a subtype of type 'GlobalKey<ScaffoldState>'

测试:
-我尝试用 showSnackbar替换 return方法，并且错误停止，但 return String不起作用。

代码 HomePage.dart:

import 'package:flutter/material.dart';
import 'package:yakoa/custom_librairies/Common.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePage createState() => _HomePage();
}

class _HomePage extends State<HomePage> {
  GlobalKey _scaffoldkey = new GlobalKey();
  @override
  Widget build(BuildContext context) {
return Scaffold(
      key: _scaffoldkey,
      body: Padding(
          padding: EdgeInsets.only(top: 200),
          child: Column(
            children: <Widget>[
              Text("Element 1",
                  style: TextStyle(
                      fontSize: 35, color: Theme.of(context).primaryColor)),
              buildSeparator(MediaQuery.of(context).size.width),
              Text("Element 1",
                  style: TextStyle(
                      fontSize: 35, color: Theme.of(context).primaryColor)),
              buildSeparator(MediaQuery.of(context).size.width)
            ],
          )),
      floatingActionButton: RaisedButton(
        child: Text("Click"),
        onPressed: () {
showSnackbar(_scaffoldkey,"yes");
        },
      ),
    );

Common.dart:

void showSnackbar(GlobalKey<ScaffoldState> scaffoldKey, String text) {
  final snackBar = SnackBar(content: Text(text));
  scaffoldKey.currentState.hideCurrentSnackBar();
  scaffoldKey.currentState.showSnackBar(snackBar);
}

谢谢，
é

Answer 1

添加GlobalKey的类型:

  GlobalKey<ScaffoldState> _scaffoldkey = new GlobalKey<ScaffoldState>();