creating the example

ex2/lib/main.dart

+import 'dart:async';
+import 'dart:convert';
+
 import 'package:flutter/material.dart';
-import 'package:http/http.dart';
+import 'package:http/http.dart' as http;
+
+Future<Album> fetchAlbum() async {
+  final response = await http
+      .get(Uri.parse('https://jsonplaceholder.typicode.com/albums/1'));
 
-void main() {
-  runApp(const MyApp());
+  if (response.statusCode == 200) {
+    // If the server did return a 200 OK response,
+    // then parse the JSON.
+    return Album.fromJson(jsonDecode(response.body));
+  } else {
+    // If the server did not return a 200 OK response,
+    // then throw an exception.
+    throw Exception('Failed to load album');
+  }
 }
 
-class MyApp extends StatelessWidget {
-  const MyApp({Key? key}) : super(key: key);
+class Album {
+  final int userId;
+  final int id;
+  final String title;
 
-  // This widg et is the root of your application.
-  @override
-  Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Flutter Demo',
-      theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // Try running your application with "flutter run". You'll see the
-        // application has a blue toolbar. Then, without quitting the app, try
-        // changing the primarySwatch below to Colors.green and then invoke
-        // "hot reload" (press "r" in the console where you ran "flutter run",
-        // or simply save your changes to "hot reload" in a Flutter IDE).
-        // Notice that the counter didn't reset back to zero; the application
-        // is not restarted.
-        primarySwatch: Colors.blue,
-      ),
-      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+  const Album({
+    required this.userId,
+    required this.id,
+    required this.title,
+  });
+
+  factory Album.fromJson(Map<String, dynamic> json) {
+    return Album(
+      userId: json['userId'],
+      id: json['id'],
+      title: json['title'],
     );
   }
 }
 
-class MyHomePage extends StatefulWidget {
-  const MyHomePage({Key? key, required this.title}) : super(key: key);
+void main() => runApp(const MyApp());
 
-  // 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;
+class MyApp extends StatefulWidget {
+  const MyApp({Key? key}) : super(key: key);
 
   @override
-  State<MyHomePage> createState() => _MyHomePageState();
+  _MyAppState createState() => _MyAppState();
 }
 
-class _MyHomePageState extends State<MyHomePage> {
-  int _counter = 0;
+class _MyAppState extends State<MyApp> {
+  late Future<Album> futureAlbum;
 
-  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++;
-    });
+  @override
+  void initState() {
+    super.initState();
+    futureAlbum = fetchAlbum();
   }
 
   @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(
+    return MaterialApp(
+      title: 'Fetch Data Example',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: Scaffold(
         appBar: AppBar(
-        // Here we take the value from the MyHomePage object that was created by
-        // the App.build method, and use it to set our appbar title.
-        title: Text(widget.title),
+          title: const Text('Fetch Data Example'),
         ),
         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.
-          //
-          // Invoke "debug painting" (press "p" in the console, choose the
-          // "Toggle Debug Paint" action from the Flutter Inspector in Android
-          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
-          // to see the wireframe for each widget.
-          //
-          // 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).
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[
-            const Text(
-              'You have pushed the button this many times:',
-            ),
-            Text(
-              '$_counter',
-              style: Theme.of(context).textTheme.headline4,
+          child: FutureBuilder<Album>(
+            future: futureAlbum,
+            builder: (context, snapshot) {
+              if (snapshot.hasData) {
+                return Text(snapshot.data!.title);
+              } else if (snapshot.hasError) {
+                return Text('${snapshot.error}');
+              }
+
+              // By default, show a loading spinner.
+              return const CircularProgressIndicator();
+            },
           ),
-          ],
         ),
       ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: _incrementCounter,
-        tooltip: 'Increment',
-        child: const Icon(Icons.add),
-      ), // This trailing comma makes auto-formatting nicer for build methods.
     );
   }
 }