lib/main.dart

@@ -1,5 +1,3 @@
-import 'dart:math';
-
 import 'package:flutter/material.dart';
 
 void main() {
@@ -9,12 +7,27 @@ void main() {
 class MyApp extends StatelessWidget {
   const MyApp({super.key});
 
+  // This widget is the root of your application.
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       title: 'Flutter Demo',
-      debugShowCheckedModeBanner: false,
       theme: ThemeData(
+        // This is the theme of your application.
+        //
+        // TRY THIS: Try running your application with "flutter run". You'll see
+        // the application has a purple toolbar. Then, without quitting the app,
+        // try changing the seedColor in the colorScheme below to Colors.green
+        // and then invoke "hot reload" (save your changes or press the "hot
+        // reload" button in a Flutter-supported IDE, or press "r" if you used
+        // the command line to start the app).
+        //
+        // Notice that the counter didn't reset back to zero; the application
+        // state is not lost during the reload. To reset the state, use hot
+        // restart instead.
+        //
+        // This works for code too, not just values: Most code changes can be
+        // tested with just a hot reload.
         colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
         useMaterial3: true,
       ),
@@ -26,6 +39,15 @@ class MyApp extends StatelessWidget {
 class MyHomePage extends StatefulWidget {
   const MyHomePage({super.key, required this.title});
 
+  // This widget is the home page of your application. It is stateful, meaning
+  // that it has a State object (defined below) that contains fields that affect
+  // how it looks.
+
+  // This class is the configuration for the state. It holds the values (in this
+  // case the title) provided by the parent (in this case the App widget) and
+  // used by the build method of the State. Fields in a Widget subclass are
+  // always marked "final".
+
   final String title;
 
   @override
@@ -34,44 +56,53 @@ class MyHomePage extends StatefulWidget {
 
 class _MyHomePageState extends State<MyHomePage> {
   int _counter = 0;
-  Color _color = Colors.orangeAccent;
 
   void _incrementCounter() {
     setState(() {
+      // This call to setState tells the Flutter framework that something has
+      // changed in this State, which causes it to rerun the build method below
+      // so that the display can reflect the updated values. If we changed
+      // _counter without calling setState(), then the build method would not be
+      // called again, and so nothing would appear to happen.
       _counter++;
-      _color =
-          Color((Random().nextDouble() * 0xFFFFFF).toInt()).withOpacity(1.0);
     });
   }
 
   @override
   Widget build(BuildContext context) {
+    // This method is rerun every time setState is called, for instance as done
+    // by the _incrementCounter method above.
+    //
+    // The Flutter framework has been optimized to make rerunning build methods
+    // fast, so that you can just rebuild anything that needs updating rather
+    // than having to individually change instances of widgets.
     return Scaffold(
       appBar: AppBar(
-        backgroundColor: _color,
+        // TRY THIS: Try changing the color here to a specific color (to
-        title: Column(
+        // Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
-          mainAxisAlignment: MainAxisAlignment.center,
+        // change color while the other colors stay the same.
-          crossAxisAlignment: CrossAxisAlignment.start,
+        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
-          children: const [
+        // Here we take the value from the MyHomePage object that was created by
-            Text(
+        // the App.build method, and use it to set our appbar title.
-              'Masenkin',
+        title: Text(widget.title),
-              style: TextStyle(
-                fontSize: 20,
-                fontWeight: FontWeight.bold,
-              ),
-            ),
-            Text(
-              'Maksim Sergeevich',
-              style: TextStyle(
-                fontSize: 12,
-                fontWeight: FontWeight.normal,
-              ),
-            ),
-          ],
-        ),
       ),
       body: Center(
+        // Center is a layout widget. It takes a single child and positions it
+        // in the middle of the parent.
         child: Column(
+          // Column is also a layout widget. It takes a list of children and
+          // arranges them vertically. By default, it sizes itself to fit its
+          // children horizontally, and tries to be as tall as its parent.
+          //
+          // Column has various properties to control how it sizes itself and
+          // how it positions its children. Here we use mainAxisAlignment to
+          // center the children vertically; the main axis here is the vertical
+          // axis because Columns are vertical (the cross axis would be
+          // horizontal).
+          //
+          // TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
+          // action in the IDE, or press "p" in the console), to see the
+          // wireframe for each widget.
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
             const Text(
@@ -81,21 +112,14 @@ class _MyHomePageState extends State<MyHomePage> {
               '$_counter',
               style: Theme.of(context).textTheme.headlineMedium,
             ),
-            if (_counter > 10)
-              Text(
-                'STOP CLICKING! \nIT\'S NOT HAMSTER COMBAT',
-                style: Theme.of(context).textTheme.headlineMedium,
-                textAlign: TextAlign.center,
-              ),
           ],
         ),
       ),
       floatingActionButton: FloatingActionButton(
         onPressed: _incrementCounter,
-        backgroundColor: _color,
         tooltip: 'Increment',
-        child: const Icon(Icons.mood),
+        child: const Icon(Icons.add),
-      ),
+      ), // This trailing comma makes auto-formatting nicer for build methods.
     );
   }
 }