Learn KOTLIN with Real Code Examples

Updated Nov 17, 2025

Introduction & Fundamentals Setup & Configuration Architecture & Deep Internals Performance & Security Development Workflow Learning & Career Growth Business & Strategy Examples

Practical Examples

Build an Android ToDo app with Jetpack Compose

Create a REST API using Ktor

Develop shared iOS+Android logic with KMP

Build desktop apps using Compose Multiplatform

Troubleshooting

Resolve null-safety type mismatches

Fix coroutine scope misuse

Handle Gradle sync issues

Fix KMP expect/actual mismatches

Testing Guide

Unit tests with KotlinTest / JUnit

Coroutine testing with runTest

Mocking with MockK

Integration tests with Ktor Test

Deployment Options

Deploy JVM backend to server or cloud

Ship Android apps to Play Store

Compile Kotlin/Native for iOS

Deploy JS bundles to web

Tools Ecosystem

IntelliJ IDEA / Android Studio

Gradle Kotlin DSL

Ktor framework

Kotlinx libraries (coroutines, serialization)

Compose Multiplatform

Integrations

Android Jetpack

Spring Boot

Ktor backend

Compose UI

SQLDelight, Exposed, Hibernate

Productivity Tips

Use IntelliJ live templates

Master scope functions

Use coroutines for async operations

Leverage Gradle Kotlin DSL

Challenges

Create a coroutine-based networking library

Build your own Kotlin DSL

Develop a KMP shared module

Create a Compose Multiplatform UI toolkit