Flutter 在线编译器

import 'package:flutter/material.dart';

void main() => runApp(const CounterApp());

class CounterApp extends StatelessWidget {
  const CounterApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(colorSchemeSeed: Colors.indigo),
      home: const CounterPage(),
    );
  }
}

class CounterPage extends StatefulWidget {
  const CounterPage({super.key});

  @override
  State<CounterPage> createState() => _CounterPageState();
}

class _CounterPageState extends State<CounterPage> {
  int _count = 0;

  void _increment() {
    setState(() => _count++);
    print('Count is now $_count');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Hello, Flutter!')),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Text('You pressed the button'),
            Text(
              '$_count',
              style: Theme.of(context).textTheme.displayLarge,
            ),
            Text(_count == 1 ? 'time' : 'times'),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _increment,
        tooltip: 'Add one',
        child: const Icon(Icons.add),
      ),
    );
  }
}