import 'package:flutter/material.dart';
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void main() => runApp(const MyApp());
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class MyApp extends StatelessWidget {
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const MyApp({Key? key}) : super(key: key);
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// This widget is the root of your application.
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@override
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Widget build(BuildContext context) {
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return MaterialApp(
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title: 'Flutter Demo',
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theme: ThemeData(
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// This is the theme of your application.
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//
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// Try running your application with "flutter run". You'll see the
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// application has a blue toolbar. Then, without quitting the app, try
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// changing the primarySwatch below to Colors.green and then invoke
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// "hot reload" (press "r" in the console where you ran "flutter run",
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// or press Run > Flutter Hot Reload in a Flutter IDE). Notice that the
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// counter didn't reset back to zero; the application is not restarted.
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primarySwatch: Colors.blue,
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),
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home: const MyHomePage(title: 'Flutter Demo Home Page'),
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);
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}
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}
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class MyHomePage extends StatefulWidget {
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const MyHomePage({Key? key, required this.title}) : super(key: key);
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// This widget is the home page of your application. It is stateful, meaning
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// that it has a State object (defined below) that contains fields that affect
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// how it looks.
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// This class is the configuration for the state. It holds the values (in this
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// case the title) provided by the parent (in this case the App widget) and
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// used by the build method of the State. Fields in a Widget subclass are
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// always marked "final".
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final String title;
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@override
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State<MyHomePage> createState() => _MyHomePageState();
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}
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class _MyHomePageState extends State<MyHomePage> {
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int _counter = 0;
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void _incrementCounter() {
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setState(() {
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// This call to setState tells the Flutter framework that something has
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// changed in this State, which causes it to rerun the build method below
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// so that the display can reflect the updated values. If we changed
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// _counter without calling setState(), then the build method would not be
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// called again, and so nothing would appear to happen.
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_counter++;
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});
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}
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@override
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Widget build(BuildContext context) {
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// This method is rerun every time setState is called, for instance as done
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// by the _incrementCounter method above.
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//
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// The Flutter framework has been optimized to make rerunning build methods
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// fast, so that you can just rebuild anything that needs updating rather
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// than having to individually change instances of widgets.
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return Scaffold(
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appBar: AppBar(
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// Here we take the value from the MyHomePage object that was created by
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// the App.build method, and use it to set our appbar title.
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title: Text(widget.title),
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),
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body: Center(
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// Center is a layout widget. It takes a single child and positions it
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// in the middle of the parent.
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child: Column(
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// Column is also a layout widget. It takes a list of children and
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// arranges them vertically. By default, it sizes itself to fit its
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// children horizontally, and tries to be as tall as its parent.
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//
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// Invoke "debug painting" (press "p" in the console, choose the
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// "Toggle Debug Paint" action from the Flutter Inspector in Android
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// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
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// to see the wireframe for each widget.
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//
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// Column has various properties to control how it sizes itself and
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// how it positions its children. Here we use mainAxisAlignment to
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// center the children vertically; the main axis here is the vertical
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// axis because Columns are vertical (the cross axis would be
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// horizontal).
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mainAxisAlignment: MainAxisAlignment.center,
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children: <Widget>[
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const Text(
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'You have pushed the button this many times:',
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),
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Text(
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'$_counter',
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style: Theme.of(context).textTheme.headline4,
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),
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],
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),
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),
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floatingActionButton: FloatingActionButton(
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onPressed: _incrementCounter,
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tooltip: 'Increment',
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child: const Icon(Icons.add),
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), // This trailing comma makes auto-formatting nicer for build methods.
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);
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}
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}
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