Flutter on @yt.yeasin50

Dart Basic Course

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

Dart Bangla Course

🎥 Checkout playlist on youtube

Coding in DartPad

dartpad

Main Method & Comments

DataTypes

Number in dart

String

Boolean

List

Map

Condition & break

If-Else

For Loop

Links:

How to start flutter

Sat, 27 Sep 2025 19:00:00 +0800

This is the very first question asked by many after they start their Flutter journey. Here I have included necessary stuff from my knowledge, not strictly limited to Flutter but including the related things as well.

I can point to a single direction from where they can start their journey as a Flutter developer.
Also, you can share to save your time as well.
Suggestions are welcome, make an issue and then PR.

Documentation

Yes, there is no better option than official Flutter documentation.

Abstract & Generic class

Sun, 23 Aug 2026 19:00:00 +0800

Abstract class

You went to your local restaurant for breakfast. When you got there, you saw a lump of raw dough sitting in front of the stove. Then a boy came over and asked, “Ruti, paratha, or naan?” Whatever you say, they prepare it right on the spot and serve it to you.

Here the dough on the counter is the abstract class.

abstract class Dough{}

It exits, but it has no final form. You can not eat it raw rough dough. In programming we would say, you can not initiate it.

Abstract & Generic class

Sun, 23 Aug 2026 19:00:00 +0800

Abstract class

Sealed & Union class

Sun, 23 Aug 2026 19:00:00 +0800

I hope you’ve already checked the Abstract & Generic . We already know what abstract class is and it can be extend from anywhere by importing the abstract class. It offered the benefits of restriction extending class outside the library.

abstract class ApiState {}

class Loading extends ApiState {}
class Success extends ApiState {}
class Error extends ApiState {}

But we create a sealed class, it can not be only extend from that library/file.

Note each file is a library, and you can use part/part of to combine multiple file.

Sealed & Union class

Sun, 23 Aug 2026 19:00:00 +0800

I hope you’ve already checked the Abstract & Generic.
We already know what abstract class is, and it can be extend from anywhere.

// api_state.dart
abstract class ApiState {}

class Loading extends ApiState {}
class Success extends ApiState {}

// api_provider.dart
class Error extends ApiState {}

Sealed class

But Sealed class restrict extending class outside the library. You can only extends it within the same library/file.

Nvim+Flutter

Fri, 08 May 2026 04:00:22 +0600

Configure Flutter

Equatable

Tue, 28 Jul 2026 19:00:00 +0800

Flutter == vs Value Equality

code

import 'package:equatable/equatable.dart';

class Contact extends Equatable {
 const Contact({required this.type, required this.value});
 final String type;
 final String value;

 @override
 List<Object?> get props => [type, value];
}

class Phone with Equatable {
 const Phone({this.isPrimary = false, this.contact});

 final bool isPrimary;
 final Contact? contact;

 @override
 List<Object?> get props => [...contact?.props ?? [], isPrimary];
}

void main() {
 Contact a = Contact(type: "phone", value: "0101");
 Contact b = Contact(type: "phone", value: "0101");

 if (a == b) {
 print("same same ....");
 } else {
 print("a: ${a.toString()}");
 print("b: ${b.toString()}");
 }
}

equatable on pub.dev↗

Json serilizable

Thu, 30 Jul 2026 19:00:00 +0800

user.dart

import 'package:example/models/contact.dart';
import 'package:json_annotation/json_annotation.dart';
part 'user.g.dart'; // the `user` is the fileName

@JsonEnum(valueField: "value")
enum Gender {
 male("m"),
 female("f");

 const Gender(this.value);
 final String value;
}

@JsonSerializable(fieldRename: FieldRename.screamingSnake)
class User {
 User({
 required this.name,
 required this.dateOfBirth,
 required this.gender,
 required this.contact,
 required this.presentAddress,
 });

 final String name;
 final Gender gender;
 @JsonKey(name: "dob")
 final DateTime? dateOfBirth;

 final Contact contact;

 final String presentAddress;

 factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
 Map<String, dynamic> toJson() => _$UserToJson(this);
}

Custom Converter

class DateTimeConverter
 implements JsonConverter<DateTime?, Map<String, dynamic>?> {
 const DateTimeConverter();

 @override
 DateTime? fromJson(Map<String, dynamic>? json) {
 if (json == null) return null;
 final second = json["seconds"];
 return DateTime.fromMillisecondsSinceEpoch(second);
 }

 @override
 Map<String, dynamic>? toJson(DateTime? object) {
 if (object == null) return null;
 return {'seconds': (object.millisecondsSinceEpoch / 1000).round()};
 }
}

Custom config `build.yaml`

targets:
 $default:
 builders:
 json_serializable:
 options:
 # Options configure how source code is generated for every
 # `@JsonSerializable`-annotated class in the package.
 #
 # The default value for each is listed.
 any_map: false
 checked: false
 constructor: ""
 create_factory: true
 create_field_map: false
 create_json_keys: false
 create_json_schema: true
 create_per_field_to_json: false
 create_to_json: true
 date_time_utc: true
 disallow_unrecognized_keys: false
 explicit_to_json: false
 field_rename: snake
 generic_argument_factories: false
 ignore_unannotated: false
 include_if_null: true

json_serializable on pub.dev↗

freezed

Wed, 05 Aug 2026 19:00:00 +0800

Flutter Freezed | Models, copyWith, JSON Serialization, Generics & Union Types

Make sure to watch json_seriliazble first.

Freezed class

address.dart

{
 "success": true,
 "data": {
 "street": "123 Main Street",
 "district": "Dhaka",
 "country": "Bangladesh"
 },
 "message": "Address fetched"
}

import 'package:freezed_annotation/freezed_annotation.dart';

part 'address.freezed.dart';
part 'address.g.dart';

@freezed
abstract class Address with _$Address {
 const factory Address({
 required String street,
 required String district,
 required String country,
 }) = _Address;

 factory Address.fromJson(Map<String, Object?> json) =>
 _$AddressFromJson(json);

 static const Address present = Address(
 street: "present",
 district: "addr.dis",
 country: "BD",
 );

 static const Address permanent = Address(
 street: "permanent",
 district: "addr.dis",
 country: "...",
 );
}

person.dart

{
 "success": true,
 "data": {
 "name": "John Doe",
 "age": 25,
 "address": "Earth",
 "skills": ["Dart", "Flutter"],
 "presentAddress": {
 "street": "123 Main Street",
 "district": "Dhaka",
 "country": "Bangladesh"
 },
 "permanentAddress": {
 "street": "45 Lake Road",
 "district": "Chattogram",
 "country": "Bangladesh"
 }
 },
 "message": "Person fetched"
}

import 'package:freezed_annotation/freezed_annotation.dart';
import 'address.dart';

part 'user.freezed.dart';
part 'user.g.dart';

@freezed
abstract class Person with _$Person {
 const factory Person({
 required String name,
 int? age,
 @Default("Eath") String? address,
 @Default([]) List<String> skills,

 required Address presentAddress,
 Address? permanentAddress,
 }) = _Person;

 factory Person.fromJson(Map<String, Object?> json) => _$PersonFromJson(json);

 static const Person ui = Person(
 name: "0",
 age: 0,
 skills: [],
 presentAddress: Address.present,
 permanentAddress: Address.permanent,
 );
}

Generic

api_response.dart

import 'package:freezed_annotation/freezed_annotation.dart';

part 'api_response.freezed.dart';
part 'api_response.g.dart';

@Freezed(genericArgumentFactories: true)
abstract class ApiResponse<T> with _$ApiResponse<T> {
 const factory ApiResponse({
 required bool success,
 T? data,
 String? message,
 }) = _ApiResponse<T>;

 factory ApiResponse.fromJson(
 Map<String, dynamic> json,
 T Function(Object?) fromJsonT,
 ) => _$ApiResponseFromJson(json, fromJsonT);
}

Union

code-snippet

We are using type instead of runtimetype

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.

Navigation with Navigator 1

Fri, 24 Jul 2026 19:00:00 +0800

Learn Flutter’s Navigator API with practical examples of push, pop, pushReplacement, pushAndRemoveUntil, popUntil, canPop, and passing data between routes.

main.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() {
 runApp(
 const MaterialApp(home: HomePage(), debugShowCheckedModeBanner: false),
 );
}

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

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 appBar: AppBar(title: const Text("Home")),
 body: Center(
 child: ElevatedButton(
 onPressed: () async {
 final route = DetailsPage.route();
 final result = await Navigator.push(context, route);
 print(result);
 },
 child: const Text("Go to Details"),
 ),
 ),
 );
 }
}

class DetailsPage extends StatelessWidget {
 const DetailsPage({super.key, required this.value});
 final int value;

 static MaterialPageRoute route() => MaterialPageRoute(
 builder: (context) => DetailsPage(value: 123),
 settings: RouteSettings(arguments: 12312),
 );

 @override
 Widget build(BuildContext context) {
 final canPop = ModalRoute.of(context)?.canPop ?? false;

 return Scaffold(
 appBar: AppBar(title: const Text("Details")),
 body: Center(
 child: Column(
 spacing: 16,
 mainAxisSize: .min,
 children: [
 if (canPop) CloseButtonIcon(),

 ElevatedButton(
 onPressed: () {
 Navigator.of(context).pop("hello");
 },
 child: const Text("pop(result)"),
 ),

 ElevatedButton(
 onPressed: () {
 Navigator.of(context).pushReplacement(SettingsPage.route());
 },
 child: const Text("Settings with pushReplacement"),
 ),

 ElevatedButton(
 onPressed: () {
 Navigator.of(context).push(SettingsPage.route());
 },
 child: const Text("Settings with push"),
 ),

 ElevatedButton(
 onPressed: () {
 Navigator.of(context).pushAndRemoveUntil(SettingsPage.route(), (
 route,
 ) {
 return false;
 });
 },
 child: const Text("pushAndRemoveUntil"),
 ),
 ],
 ),
 ),
 );
 }
}

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

 static MaterialPageRoute route() =>
 MaterialPageRoute(builder: (_) => SettingsPage());

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 appBar: AppBar(title: const Text("Settings")),
 body: Center(
 child: Column(
 mainAxisSize: .min,
 children: [
 ElevatedButton(
 onPressed: () {
 Navigator.of(context).popUntil((route) {
 return route.isFirst;
 });
 },
 child: const Text("popUntil(Home)"),
 ),

 ElevatedButton(
 onPressed: () {
 debugPrint("canPop: ${Navigator.canPop(context)}");
 Navigator.maybePop(context);
 },
 child: const Text("canPop / maybePop"),
 ),
 ],
 ),
 ),
 );
 }
}

Flutter Go-Router

Tue, 20 Oct 2026 19:00:00 +0600

GoRouter in Flutter

go_router on pub.dev↗

Source Code

Setup, Route Configuration & Sub-Routes

Previous Navigator 2.0 implementation: https://github.com/yeasin50/lisa_fischer

Path Parameters, Query Parameters & Exit Dialog

Redirection & Async Redirects

Saving key-value pair

Wed, 19 Aug 2026 19:00:00 +0800

Shared_preferences

Persistent theme with Shared_preference.

this is part of flutter_workshop provider

shared_preferences on pub.dev↗

Sqlfite: Persistent todo app

Thu, 17 Sep 2026 19:00:00 +0800

Let’s create a simple todo CRUD application with sqlfite

sqflite on pub.dev↗

Checkout Starter code or final code

Project setup

You can create a new project or just clone the repo.

I am using freezed to generate my classes. You can explore my video on freezed or use normal class and create fromJson/toMap method.

Hive: Flutter Local Storage

Thu, 01 Oct 2026 19:00:00 +0800

Database Setup & Custom Adapters

hive_ce on pub.dev↗

dependencies:
 hive_ce: latest
 hive_ce_flutter: latest

Basic

basic hive

import 'package:flutter/material.dart';

import 'package:hive_ce_flutter/hive_flutter.dart';

void main() async {
 await Hive.initFlutter();
 await Hive.openBox("fruits");

 runApp(
 MaterialApp(
 debugShowCheckedModeBanner: false,
 home: Scaffold(body: const MyApp()),
 darkTheme: ThemeData.dark(),
 themeMode: .dark,
 ),
 );
}

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

 @override
 State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
 final box = Hive.box("fruits");

 @override
 Widget build(BuildContext context) {
 return Column(
 spacing: 24,
 crossAxisAlignment: .stretch,
 mainAxisAlignment: .center,
 children: [
 Text(
 box.get("isDarkMode", defaultValue: false).toString(),
 textAlign: .center,
 ),

 TextButton(
 onPressed: () {
 box.put("isDarkMode", null);
 setState(() {});
 },
 child: Text("save"),
 ),

 TextButton(
 onPressed: () {
 box.delete("isDarkMode");
 setState(() {});
 },
 child: Text("delete"),
 ),
 ],
 );
 }
}

Box<T>

type specific counter

import 'package:flutter/material.dart';
import 'package:hive_ce/hive.dart';
import 'package:hive_ce_flutter/hive_ce_flutter.dart';

void main() async {
 await Hive.initFlutter();
 await Hive.openBox<int>('counter');

 runApp(
 MaterialApp(
 home: const MyApp(),
 darkTheme: ThemeData.dark(),
 themeMode: .dark,
 ),
 );
}

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

 @override
 State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
 final counter = Hive.box<int>('counter');

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 body: Padding(
 padding: .all(8.0),
 child: ElevatedButton(
 onPressed: () {
 counter.put("v1", counter.get("v1", defaultValue: 0)! + 1);
 setState(() {}); // to refresh the ui
 },
 child: Text("counter ${counter.get("v1").toString()}"),
 ),
 ),
 );
 }
}

Custom adapter

import 'package:flutter/material.dart';
import 'package:hive_ce/hive.dart';
import 'package:hive_ce_flutter/hive_ce_flutter.dart';

class User {
 new({required this.name, required this.dob});

 final String name;
 final DateTime dob;
 @override
 String toString() {
 return "User(name: $name, dob: $dob)";
 }
}

class UserAdapter extends TypeAdapter<User> {
 @override
 final int typeId = 0;

 @override
 User read(BinaryReader reader) {
 return User(name: reader.read(), dob: reader.read());
 }

 @override
 void write(BinaryWriter writer, User obj) {
 writer.write(obj.name);
 writer.write(obj.dob);
 }
}

void main() async {
 await Hive.initFlutter();

 Hive.registerAdapter(UserAdapter());
 await Hive.openBox<User>('users');

 runApp(
 MaterialApp(
 home: const MyApp(),
 darkTheme: ThemeData.dark(),
 themeMode: .dark,
 ),
 );
}

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

 @override
 State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
 final controller = TextEditingController();
 final userBox = Hive.box<User>("users");

 void add() async {
 await userBox.put(0, User(name: controller.text, dob: DateTime.now()));
 setState(() {});
 }

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 body: Center(
 child: Padding(
 padding: .all(8.0),
 child: Column(
 spacing: 24,
 crossAxisAlignment: .stretch,
 mainAxisSize: .min,
 children: [
 Text(userBox.get(0).toString()),

 TextFormField(
 controller: controller,
 decoration: InputDecoration(border: OutlineInputBorder()),
 ),
 ElevatedButton(onPressed: add, child: Text("add user")),
 ],
 ),
 ),
 ),
 );
 }
}

Generate adapter

To generate adapters, use hive_ce_generator and build_runner.

Flutter on @yt.yeasin50

Dart Basic Course

Dart Bangla Course

Coding in DartPad

Main Method & Comments

DataTypes

Number in dart

String

Boolean

List

Map

Condition & break

If-Else

For Loop

How to start flutter

Documentation

Abstract & Generic class

Abstract class

Abstract & Generic class

Abstract class

Sealed & Union class

Sealed & Union class

Sealed class

Nvim+Flutter

Equatable

Flutter == vs Value Equality

Json serilizable

Custom config build.yaml

freezed

Freezed class

Generic

Union

Understaing State & Updating UI

Who Owns the State?

Callbacks & typedef

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

FutureBuilder & StreamBuilder

FutureBuilder

StreamBuilder

App-State with Provider

Code

Shared_preference

Navigation with Navigator 1

Flutter Go-Router

Saving key-value pair

Shared_preferences

Sqlfite: Persistent todo app

Project setup

Hive: Flutter Local Storage

Basic

Box<T>

Custom adapter

Generate adapter

Custom config `build.yaml`

Callbacks & `typedef`