如何在Flutter中的下一页上将计数加1？

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    // 构建界面的代码
  }
}

FlatButton(
  onPressed: () {
    setState(() {
      _counter++;
    });
  },
  child: Text('下一页'),
),

Text('计数值：$_counter'),

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              '计数值：$_counter',
              style: TextStyle(fontSize: 24),
            ),
            SizedBox(height: 16),
            FlatButton(
              onPressed: () {
                setState(() {
                  _counter++;
                });
              },
              child: Text('下一页'),
            ),
          ],
        ),
      ),
    );
  }
}