State-management on @yt.yeasin50

Understaing State & Updating UI

Thu, 09 Jul 2026 19:00:00 +0800

Who Owns the State?

Callbacks & `typedef`

Parent ↔ Child Communication

code snippet

import 'dart:math';

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
 const MyApp({super.key});

 @override
 Widget build(BuildContext context) {
 return MaterialApp(
 theme: ThemeData(colorScheme: .fromSeed(seedColor: Colors.deepPurple)),
 home: const MyHomePage(),
 );
 }
}

class MyHomePage extends StatefulWidget {
 const MyHomePage({super.key});

 @override
 State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
 int _counter = 0;

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 body: Column(
 crossAxisAlignment: .stretch,
 children: [
 SectionView(
 onTap: (v) async {
 _counter = v;
 setState(() {});
 return "Something went wrong";
 },
 ),
 Text(
 _counter.toString(),
 style: TextStyle(fontSize: 55),
 textAlign: .center,
 ),
 SectionView(
 increment: false,
 onTap: (n) async {
 _counter = n;

 await Future.delayed(Duration(seconds: 2));
 setState(() {});
 return "";
 },
 ),
 ],
 ),
 );
 }
}

typedef OnSectionViewChange = Future<String> Function(int);

class SectionView extends StatefulWidget {
 const SectionView({super.key, this.increment = true, required this.onTap});
 final bool increment;

 final OnSectionViewChange onTap;

 @override
 State<SectionView> createState() => _SectionViewState();
}

class _SectionViewState extends State<SectionView> {
 bool isLoading = false;

 String errMsg = "";
 Future<void> onTap() async {
 isLoading = true;
 setState(() {});

 Random random = Random();
 final number = random.nextInt(4444);

 errMsg = await widget.onTap(widget.increment ? number : number * -1);

 isLoading = false;
 setState(() {});
 }

 @override
 Widget build(BuildContext context) {
 return Expanded(
 child: Material(
 color: widget.increment ? Colors.blueAccent : Colors.redAccent,
 child: Center(
 child: Column(
 mainAxisSize: .min,
 children: [
 Text(errMsg),
 InkWell(
 onTap: isLoading ? null : onTap,
 child: isLoading
 ? Center(child: CircularProgressIndicator())
 : Icon(
 widget.increment ? Icons.add : Icons.remove,
 size: 55,
 ),
 ),
 ],
 ),
 ),
 ),
 );
 }
}

Why AlertDialog/BottomSheet UI doesn’t update even with setState

Widget state 03

FutureBuilder & StreamBuilder

Thu, 09 Jul 2026 19:00:00 +0800

FutureBuilder

Learn Async Data & avoid common mistakes.

future codeSnippet

import 'dart:math';

import 'package:flutter/material.dart';

void main() => runApp(
 const MaterialApp(debugShowCheckedModeBanner: false, home: MyHomePage()),
);

class MyHomePage extends StatefulWidget {
 const MyHomePage({super.key});

 @override
 State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
 //...
 Future<int> fetchData() async {
 await Future.delayed(Duration(seconds: 4));
 final number = Random().nextInt(100);
 return number;
 }

 late Future<int> future = fetchData();

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 body: Center(
 child: FutureBuilder<int>(
 future: future,
 initialData: 100,
 builder: (context, AsyncSnapshot snapshot) {
 if (snapshot.hasError) {
 return Text(snapshot.error?.toString() ?? "");
 }

 return Column(
 mainAxisSize: .min,
 children: [
 if (snapshot.connectionState == ConnectionState.waiting)
 CircularProgressIndicator(),
 Text(snapshot.data.toString()),
 ],
 );
 },
 ),
 ),
 );
 }
}

StreamBuilder

Flutter’s Stream and StreamBuilder in detail. It also shows StreamController, StreamSubscription, stream error handling, single-subscription issue and event management with practical examples.

App-State with Provider

Thu, 13 Aug 2026 19:00:00 +0600

This video covers Provider in Flutter, including ChangeNotifier, ProxyProvider, FutureProvider, StreamProvider, DevTools, and common Provider mistakes.

Code

Clone the starter codebase
Switch to the provider-start branch
Continue from there

Or just watch the video:

Shared_preference

Persistent theme with Shared_preference.