问从另一个文件返回到main.dart中的类

EN

class ArViewState extends State<ArViewWidget> with WidgetsBindingObserver {
.
.
.
    Future<void> onArchitectWidgetCreated() async {
        this.architectWidget.setJSONObjectReceivedCallback((jsonObjectReceived) {
        // I want to go back to the TopPage class in main.dart here.
        // however how can I do that?? my code is like this below.

            return Navigator.pushReplacement(context,
            NoAnimationMaterialPageRoute(
                builder: (context) => TopPage()));

import arview.dart;

class TopPage extends StatefulWidget {
  TopPage({Key key, this.title}) : super(key: key);
  final String title;
  @override
  _TopPageState createState() => _TopPageState();
}

class _TopPageState extends State<TopPage> {
  Widget aboutButton(num){
    return Expanded(
      child:FlatButton(
        padding:EdgeInsets.only(bottom:10,right:5,left:5,top:10),
        child:  Image.asset("mybtn.png");
      ),
    );
  }