如何在Flutter (Dart)中更改文本？

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  String myText = 'Hello World';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Text Change Example'),
        ),
        body: Center(
          child: Container(
            child: Text(myText),
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            myText = 'New Text';
          },
          child: Icon(Icons.edit),
        ),
      ),
    );
  }
}