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| 1 | +import 'package:flutter/material.dart'; |
| 2 | + |
| 3 | +void main() { |
| 4 | + runApp(MyApp()); |
| 5 | +} |
| 6 | + |
| 7 | +class MyApp extends StatelessWidget { |
| 8 | + // This widget is the root of your application. |
| 9 | + @override |
| 10 | + Widget build(BuildContext context) { |
| 11 | + return MaterialApp( |
| 12 | + title: 'Flutter Demo', |
| 13 | + theme: ThemeData( |
| 14 | + // This is the theme of your application. |
| 15 | + // |
| 16 | + // Try running your application with "flutter run". You'll see the |
| 17 | + // application has a blue toolbar. Then, without quitting the app, try |
| 18 | + // changing the primarySwatch below to Colors.green and then invoke |
| 19 | + // "hot reload" (press "r" in the console where you ran "flutter run", |
| 20 | + // or simply save your changes to "hot reload" in a Flutter IDE). |
| 21 | + // Notice that the counter didn't reset back to zero; the application |
| 22 | + // is not restarted. |
| 23 | + primarySwatch: Colors.blue, |
| 24 | + ), |
| 25 | + home: MyHomePage(title: 'Flutter Demo Home Page'), |
| 26 | + ); |
| 27 | + } |
| 28 | +} |
| 29 | + |
| 30 | +class MyHomePage extends StatefulWidget { |
| 31 | + MyHomePage({Key? key, required this.title}) : super(key: key); |
| 32 | + |
| 33 | + // This widget is the home page of your application. It is stateful, meaning |
| 34 | + // that it has a State object (defined below) that contains fields that affect |
| 35 | + // how it looks. |
| 36 | + |
| 37 | + // This class is the configuration for the state. It holds the values (in this |
| 38 | + // case the title) provided by the parent (in this case the App widget) and |
| 39 | + // used by the build method of the State. Fields in a Widget subclass are |
| 40 | + // always marked "final". |
| 41 | + |
| 42 | + final String title; |
| 43 | + |
| 44 | + @override |
| 45 | + _MyHomePageState createState() => _MyHomePageState(); |
| 46 | +} |
| 47 | + |
| 48 | +class _MyHomePageState extends State<MyHomePage> { |
| 49 | + int _counter = 0; |
| 50 | + |
| 51 | + void _incrementCounter() { |
| 52 | + setState(() { |
| 53 | + // This call to setState tells the Flutter framework that something has |
| 54 | + // changed in this State, which causes it to rerun the build method below |
| 55 | + // so that the display can reflect the updated values. If we changed |
| 56 | + // _counter without calling setState(), then the build method would not be |
| 57 | + // called again, and so nothing would appear to happen. |
| 58 | + _counter++; |
| 59 | + }); |
| 60 | + } |
| 61 | + |
| 62 | + @override |
| 63 | + Widget build(BuildContext context) { |
| 64 | + // This method is rerun every time setState is called, for instance as done |
| 65 | + // by the _incrementCounter method above. |
| 66 | + // |
| 67 | + // The Flutter framework has been optimized to make rerunning build methods |
| 68 | + // fast, so that you can just rebuild anything that needs updating rather |
| 69 | + // than having to individually change instances of widgets. |
| 70 | + return Scaffold( |
| 71 | + appBar: AppBar( |
| 72 | + // Here we take the value from the MyHomePage object that was created by |
| 73 | + // the App.build method, and use it to set our appbar title. |
| 74 | + title: Text(widget.title), |
| 75 | + ), |
| 76 | + body: Center( |
| 77 | + // Center is a layout widget. It takes a single child and positions it |
| 78 | + // in the middle of the parent. |
| 79 | + child: Column( |
| 80 | + // Column is also a layout widget. It takes a list of children and |
| 81 | + // arranges them vertically. By default, it sizes itself to fit its |
| 82 | + // children horizontally, and tries to be as tall as its parent. |
| 83 | + // |
| 84 | + // Invoke "debug painting" (press "p" in the console, choose the |
| 85 | + // "Toggle Debug Paint" action from the Flutter Inspector in Android |
| 86 | + // Studio, or the "Toggle Debug Paint" command in Visual Studio Code) |
| 87 | + // to see the wireframe for each widget. |
| 88 | + // |
| 89 | + // Column has various properties to control how it sizes itself and |
| 90 | + // how it positions its children. Here we use mainAxisAlignment to |
| 91 | + // center the children vertically; the main axis here is the vertical |
| 92 | + // axis because Columns are vertical (the cross axis would be |
| 93 | + // horizontal). |
| 94 | + mainAxisAlignment: MainAxisAlignment.center, |
| 95 | + children: <Widget>[ |
| 96 | + Text( |
| 97 | + 'You have pushed the button this many times:', |
| 98 | + ), |
| 99 | + Text( |
| 100 | + '$_counter', |
| 101 | + style: Theme.of(context).textTheme.headline4, |
| 102 | + ), |
| 103 | + ], |
| 104 | + ), |
| 105 | + ), |
| 106 | + floatingActionButton: FloatingActionButton( |
| 107 | + onPressed: _incrementCounter, |
| 108 | + tooltip: 'Increment', |
| 109 | + child: Icon(Icons.add), |
| 110 | + ), // This trailing comma makes auto-formatting nicer for build methods. |
| 111 | + ); |
| 112 | + } |
| 113 | +} |
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