1. import 'package:flutter/material.dart';
    2. import 'package:english_words/english_words.dart';
    4. void main() => runApp(MyApp());
    6. class MyApp extends StatelessWidget {
    7.   // This widget is the root of your application.
    8.   @override
    9.   Widget build(BuildContext context) {
    10.     return MaterialApp(
    11.       title: 'Flutter Demo',
    12.       theme: ThemeData(
    13.         // This is the theme of your application.
    14.         //
    15.         // Try running your application with "flutter run". You'll see the
    16.         // application has a blue toolbar. Then, without quitting the app, try
    17.         // changing the primarySwatch below to Colors.green and then invoke
    18.         // "hot reload" (press "r" in the console where you ran "flutter run",
    19.         // or simply save your changes to "hot reload" in a Flutter IDE).
    20.         // Notice that the counter didn't reset back to zero; the application
    21.         // is not restarted.
    22.         primarySwatch: Colors.blue,
    23.       ),
    24.       home: MyHomePage(title: 'Flutter Demo Home Page'),
    25.     );
    26.   }
    27. }
    29. class MyHomePage extends StatefulWidget {
    30.   MyHomePage({Key key, this.title}) : super(key: key);
    32.   // This widget is the home page of your application. It is stateful, meaning
    33.   // that it has a State object (defined below) that contains fields that affect
    34.   // how it looks.
    36.   // This class is the configuration for the state. It holds the values (in this
    37.   // case the title) provided by the parent (in this case the App widget) and
    38.   // used by the build method of the State. Fields in a Widget subclass are
    39.   // always marked "final".
    41.   final String title;
    43.   @override
    44.   _MyHomePageState createState() => _MyHomePageState();
    45. }
    47. class _MyHomePageState extends State<MyHomePage> {
    48.   int _counter = 0;
    50.   void _incrementCounter() {
    51.     setState(() {
    52.       // This call to setState tells the Flutter framework that something has
    53.       // changed in this State, which causes it to rerun the build method below
    54.       // so that the display can reflect the updated values. If we changed
    55.       // _counter without calling setState(), then the build method would not be
    56.       // called again, and so nothing would appear to happen.
    57.       _counter++;
    58.     });
    59.   }
    61.   @override
    62.   Widget build(BuildContext context) {
    63.     // This method is rerun every time setState is called, for instance as done
    64.     // by the _incrementCounter method above.
    65.     //
    66.     // The Flutter framework has been optimized to make rerunning build methods
    67.     // fast, so that you can just rebuild anything that needs updating rather
    68.     // than having to individually change instances of widgets.
    69.     return Scaffold(
    70.       appBar: AppBar(
    71.         // Here we take the value from the MyHomePage object that was created by
    72.         // the App.build method, and use it to set our appbar title.
    73.         title: Text(widget.title),
    74.       ),
    75.       body: Center(
    76.         // Center is a layout widget. It takes a single child and positions it
    77.         // in the middle of the parent.
    78.         child: Column(
    79.           // Column is also layout widget. It takes a list of children and
    80.           // arranges them vertically. By default, it sizes itself to fit its
    81.           // children horizontally, and tries to be as tall as its parent.
    82.           //
    83.           // Invoke "debug painting" (press "p" in the console, choose the
    84.           // "Toggle Debug Paint" action from the Flutter Inspector in Android
    85.           // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
    86.           // to see the wireframe for each widget.
    87.           //
    88.           // Column has various properties to control how it sizes itself and
    89.           // how it positions its children. Here we use mainAxisAlignment to
    90.           // center the children vertically; the main axis here is the vertical
    91.           // axis because Columns are vertical (the cross axis would be
    92.           // horizontal).
    93.           mainAxisAlignment: MainAxisAlignment.center,
    94.           children: <Widget>[
    95.             Text(
    96.               'You have pushed the button this many times: hs i world !',
    97.             ),
    98.             Text(
    99.               '$_counter',
    100.               style: Theme.of(context).textTheme.display1,
    101.             ),
    102.           ],
    103.         ),
    104.       ),
    105.       floatingActionButton: FloatingActionButton(
    106.         onPressed: _incrementCounter,
    107.         tooltip: 'Increment',
    108.         child: Icon(Icons.add),
    109.       ), // This trailing comma makes auto-formatting nicer for build methods.
    110.     );
    111.   }
    112. }