Kotlin Programming Tutorials

What is Kotlin? — Complete Beginner's Guide

Kotlin is a modern statically typed language for JVM, Android, JavaScript, and native development, combining OOP and functional programming.

Kotlin Installation — Complete Setup Guide

Install Kotlin on Windows, macOS, and Linux with SDKMAN, Homebrew, or manual methods. Set up IntelliJ IDEA and Android Studio for Kotlin development.

Kotlin Basics — Variables, Data Types, and Syntax Guide

Learn Kotlin basics: variables, data types, type inference, strings, operators, and basic I/O with practical examples for beginners.

Kotlin Control Flow — If, When, and Loops Guide

Kotlin control flow with if expressions, when statements, for loops, while loops, and ranges. Learn branching and iteration with practical examples.

Kotlin Functions — Complete Guide with Examples

Learn Kotlin functions: declaration syntax, parameters, default values, named arguments, varargs, higher-order functions, lambdas, and scope functions.

Kotlin Null Safety — Complete Guide with Examples

Kotlin null safety eliminates NullPointerException with nullable types, safe calls, the Elvis operator, and the not-null assertion operator.

Kotlin Collections — Lists, Sets, and Maps Guide

Kotlin collections: mutable and immutable lists, sets, maps, iterators, and functional operations like filter, map, and reduce with practical examples.

Kotlin Lambdas — Higher-Order Functions and Closures Guide

Kotlin lambdas as function literals, trailing lambda syntax, capturing variables, anonymous functions, and higher-order functions with practical examples.

Kotlin Classes — Object-Oriented Programming Guide

Kotlin classes with constructors, properties, init blocks, member functions, visibility modifiers, and companion objects for object-oriented programming.

Kotlin Inheritance — Complete Guide with Examples

Kotlin inheritance with open classes, override, super, abstract classes, sealed classes, and virtual functions. Learn class hierarchies and polymorphism in Kotlin.

Kotlin Interfaces — Complete Guide with Examples

Kotlin interfaces with abstract and default methods, properties, multiple interface inheritance, conflicts resolution, and functional (SAM) interfaces.

Kotlin Data Classes — Complete Guide with Examples

Kotlin data classes automatically generate equals, hashCode, toString, copy, and componentN functions. Learn data class syntax, rules, and best practices.

Kotlin Objects — Singletons, Companion Objects, and Anonymous Classes

Kotlin object declarations for singletons, companion objects for static members, object expressions for anonymous classes with practical examples.

Kotlin Sealed Classes — Complete Guide with Examples

Kotlin sealed classes and interfaces for restricted hierarchies, exhaustive when expressions, and state modeling with practical patterns and examples.

Kotlin Extensions — Extension Functions and Properties Guide

Kotlin extension functions and properties add new behavior to existing classes without inheritance. Learn extension syntax, companion extensions, and scope.

Kotlin Generics — Type Parameters and Variance Explained

Kotlin generics with type parameters, in and out variance, reified type parameters, type constraints, and star projections for type-safe reusable code.

Kotlin Android Setup — Complete Development Environment Guide

Set up Android Studio for Kotlin development, configure Gradle with Kotlin plugins, create your first Android project, and run on emulator or device.

Kotlin Activities and Fragments — Android UI Management Guide

Android activities and fragments in Kotlin: lifecycle management, navigation between screens, configuration changes, and communication patterns.

Jetpack Compose Basics — Kotlin Declarative UI Guide

Jetpack Compose basics with Kotlin: composable functions, state management, modifiers, layouts, and recomposition for modern Android UI development.

Jetpack Compose Layout — Column, Row, Box, and Modifier Guide

Jetpack Compose layout system with Column, Row, Box, LazyColumn, LazyRow, and modifier chains for building complex responsive Android UIs.

Kotlin ViewModel — Android State Management Guide

Android ViewModel in Kotlin manages UI state across configuration changes, provides coroutine scopes, and integrates with Compose and LiveData.

Kotlin Room Database — Android Local Persistence Guide

Room database in Kotlin: entities, DAOs, database class, type converters, migrations, and integration with Flow and coroutines for reactive queries.

Kotlin Retrofit — HTTP Client and API Integration Guide

Retrofit HTTP client in Kotlin with type-safe API interfaces, Moshi/Gson converters, coroutine suspend functions, interceptor chains, and error handling.

Kotlin Navigation Component — Android Screen Navigation Guide

Android Navigation Component in Kotlin with NavHost, NavController, type-safe arguments, deep linking, bottom navigation, and back stack management.

Kotlin Coroutines — Asynchronous Programming Guide

Kotlin coroutines for async programming: launch, async, await, coroutineScope, dispatchers, structured concurrency, exception handling, and channel.

Kotlin Flow — Reactive Data Streams Guide

Kotlin Flow for reactive programming: cold streams, operators like map and filter, flow builders, StateFlow, SharedFlow, and testing flows.

Kotlin Multiplatform Basics — Shared Code Across Platforms

Kotlin Multiplatform (KMP) shares business logic across Android, iOS, web, and desktop with expect/actual declarations, common modules, and platform-specific code.

Kotlin Ktor — Server-Side Development Guide

Ktor is a Kotlin framework for building asynchronous servers and clients with routing, content negotiation, authentication, WebSockets, and structured concurrency.

Kotlin Testing — Unit and Integration Testing Guide

Kotlin testing with kotlin.test, JUnit 5, MockK for mocking, coroutine testing with runTest, and integration testing for Android and Ktor applications.

Kotlin Dependency Injection — Hilt and Koin Guide

Dependency injection in Kotlin with Hilt (Android) and Koin (multiplatform): modules, scopes, qualifiers, ViewModel injection, and testing with mocked dependencies.

Kotlin CLI Tool Project — Build a Command-Line Application

Build a Kotlin CLI tool with argument parsing, file I/O, coroutines, kotlinx-cli, and GraalVM native-image compilation for fast startup times.

Kotlin Android App Project — Build a Full-Featured Application

Build a complete Kotlin Android app with Jetpack Compose, Room database, Retrofit networking, ViewModel, Navigation, Hilt DI, and Material 3 design.

Jetpack Compose UI Project — Complete Hands-On Tutorial

Build a complete Jetpack Compose UI project in Kotlin with state management, navigation, theming, and Material Design 3 components.

Ktor REST API Project — Complete Backend Tutorial

Build a complete REST API with Ktor and Kotlin featuring routing, serialization, dependency injection, authentication, and database integration.

Kotlin Multiplatform Project — Shared Code Tutorial

Build a complete Kotlin Multiplatform app with shared business logic across Android, iOS, and web using Compose Multiplatform and platform-specific UI.

Test-Driven Development with Kotest — Complete Kotlin Testing Guide

Master Test-Driven Development in Kotlin using Kotest with property-based testing, data-driven tests, coroutine testing, and mocking for robust applications.

Spring Boot with Kotlin — Complete Backend Development Guide

Build production-grade REST APIs with Spring Boot and Kotlin using JPA, security, validation, and reactive programming with WebFlux.

Arrow Functional Programming in Kotlin — Complete Guide

Learn functional programming in Kotlin with Arrow library covering Either, Option, Validated, IO, lenses, and type-safe error handling.

Kotlin Ecosystem Overview — Tools, Libraries, and Community

Explore the complete Kotlin ecosystem including build tools, testing frameworks, multiplatform targets, IDEs, community resources, and production-ready libraries.