Simple Flutter token cache Validation

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  late Future<bool> _myFuture;

  @override
  void initState() {
    super.initState();
    _myFuture = _validateToken();
  }

  Future<bool> _validateToken() async {
    // SharedPreferences prefs = await SharedPreferences.getInstance();
    // final token = prefs.getString('userToken');
    final String? token =
        await Future.delayed(const Duration(seconds: 2), () => 'userToken');
    if (token != null) {
      return true;
    }
    return false;
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: FutureBuilder<bool>(
        future: _myFuture,
        builder: (BuildContext context, AsyncSnapshot<bool> snapshot) {
          if (snapshot.hasData) {
            if (snapshot.data!) {
              return const HomePage();
            } else {
              return const LoginPage();
            }
          }
          return const LoadingPage();
        },
      ),
    );
  }
}

class LoadingPage extends StatelessWidget {
  const LoadingPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(body: Center(child: CircularProgressIndicator()));
  }
}

class LoginPage extends StatelessWidget {
  const LoginPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(body: Center(child: Text('Login Page')));
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return const Scaffold(body: Center(child: Text('Home Page')));
  }
}