Alexis Kestler
Learning Kotlin, the official language for Android development, is a wise investment for any developer today. With over 71% market share, Android is clearly the dominant mobile OS globally.
As an experienced programmer and technology enthusiast, I‘ve explored numerous resources to master Kotlin myself. In this comprehensive 3500+ word guide, I‘ll share the best of them so you can become a Kotlin pro efficiently.
Why Kotlin is Essential for Mobile Developers
Before jumping into the learning resources, let‘s first understand why Kotlin has become so invaluable for mobile app development:
Multiplatform Support
A key advantage of Kotlin is its multiplatform support. You can use the same Kotlin codebase for Android, iOS, web, backend, desktop etc. This simplifies development significantly.
For instance, you can write the business logic once in Kotlin and reuse it across platforms. This results in huge savings of time, effort and cost.
Interoperability with Java
Kotlin and Java have excellent interoperability. You can conveniently use Kotlin code in Java projects and vice versa without issues.
This allows you to gradually introduce Kotlin into existing Java codebases. So you can leverage your Java experience while coding in Kotlin.
Functional Programming Capabilities
Kotlin provides first-class support for important functional programming concepts like higher order functions, lambdas, lazy evaluation etc.
This makes code more concise, reusable and easily testable.
Null Safety
A common source of app crashes is NullPointerExceptions. Kotlin eliminates this issue using its null safety feature.
Variables in Kotlin are non-nullable by default. You have to explicitly declare them nullable if needed. This makes apps safer.
Coroutines
Kotlin coroutines provide an elegant way to handle concurrency. They allow writing asynchronous code in a sequential manner making logic easy to understand.
Using coroutines improves app performance and responsiveness. Apps can smoothly do blocking tasks without freezing the UI.
Backed by Google
Google endorsing Kotlin as a first class language for Android development gives it a huge advantage.
Google is heavily investing in Kotlin and adding new features to Android Studio and tooling to optimize Kotlin development.
As you can see, Kotlin offers powerful capabilities that supercharge your productivity and allow writing high quality mobile apps efficiently.
Now let‘s explore the top online courses and other materials to master it quickly.
Best Courses to Learn Kotlin Basics
I recommend starting with these courses to build a strong base in Kotlin syntax, tools and OOP concepts:
Kotlin Bootcamp for Programmers – Udacity
Udacity‘s popular free course is a Kotlin bootcamp developed in partnership with Google. It provides a solid foundation through interactive code lessons built using Google best practices.
Key Highlights
- Beginner Friendly
- Created by Google
- 6 Lessons totaling ~10 hours
- Integrated Playground
- Certification upon completion
Kotlin Course – FreeCodeCamp (YouTube)
For a free video course, checkout this 8 hour Kotlin tutorial by FreeCodeCamp. It covers all basics like data types, functions, classes, null safety etc. in an easy to grasp manner.
Key Highlights
- Free access
- Clear explanations
- Sample code projects
- Available as YouTube playlist
- 8 hours of comprehensive content
Kotlin for Beginners: Next Android Platform Language – Udemy
This inexpensive Udemy course provides a quick yet solid introduction to Kotlin. It covers language syntax, tools, OOP concepts, null safety, lambdas etc. in just 4 hours.
Key Highlights
- Concise 4 hour course
-Coding exercises after each section - Beginner-friendly pace
- Learn Kotlin IDEs – IntelliJ IDEA & Android Studio
- Lifetime access
Atomic Kotlin
Atomic Kotlin offers a modern way to learn Kotlin interactively through over 200 browser-based lessons. Each lesson focuses on a single concept and is explained clearly. First 6 chapters are free.
Key Highlights
- Concise lessons
- Browser-based interactivity
- Code examples
- Covers basics to advanced concepts
- First 6 chapters free
These courses will equip you with a strong understanding of Kotlin basics which is vital before diving deeper.
Comprehensive Kotlin Courses
After getting the basics right, you can take more extensive courses to gain an all-round expertise in Kotlin:
The Complete Android 12 & Kotlin Development Masterclass – Udemy
One of Udemy‘s top rated courses with over 100,000 enrollments, this 47 hour Masterclass provides advanced level training on Android app development using Kotlin.
Key Highlights
- 47 hours of video content
- Resources available for lifetime
- Real-world app projects
- Integrating Firebase cloud services
- Publishing apps on Play Store
Kotlin Bootcamp for Programmers – Google Developers
Google‘s own Kotlin course comprises 7 codelabs covering all key features like lambdas, null safety, coroutines etc. Codelabs provide interactive coding experience right in the browser.
Key Highlights
- Created by Google experts
- 7 hands-on codelabs
- Integrated code editor
- Certification from Google
- Completely free access
Kotlin for Java Developers – JetBrains Academy
This Kotlin course by JetBrains (creators of Kotlin) teaches Kotlin by making direct comparisons with Java. Suitable for experienced Java devs.
Key Highlights
- Project based learning
- Compare Kotlin and Java side-by-side
- Created by Kotlin inventors
- Covers OOP, coroutines etc.
- 7 day free trial
Functional Programming in Kotlin – Udacity
For developers keen to leverage functional programming techniques in Kotlin, this free course by Udacity is quite useful. It teaches important concepts like immutability, higher order functions, lazy evaluation, monads etc.
Key Highlights
- Created in partnership with Google
- Free access
- Intermediate level
- Hands-on coding exercises
- 2 weeks long with flexible schedule
As you can see, these courses deliver extensive training across key areas like Android development, functional programming, comparison with Java etc. This builds a strong overall proficiency in Kotlin.
Kotlin Books for In-Depth Learning
Books allow learning at your own pace and provide comprehensive coverage of a language. Here are some top Kotlin books:
Kotlin in Action
The definitive guide for learning Kotlin in depth. The second edition is fully updated for latest Kotlin features and best practices.
Key Highlights
- Written by Kotlin creators Dmitry Jemerov and Svetlana Isakova
- Authoritative coverage of language concepts
- Advanced topics like DSLs, metaprogramming etc.
- 350 pages of rich content and examples
- Covers Kotlin for server-side, Android and multiplatform
Atomic Kotlin
Breaks Kotlin into 200 self-contained interactive lessons. Each lesson focuses on a single concept and is explained clearly.
Key Highlights
- Concise and well-structured
- Includes coding examples
- Covers basics to advanced features
- Browser-based interactive delivery
- First 6 chapters available for free
Kotlin Apprentice
Teaches Kotlin in a hands-on manner by guiding you to build four complete Android apps from scratch.
Key Highlights
- Project-driven learning approach
- Covers language basics to advanced features
- Includes coroutines, Android architecture components etc.
- Sample app code available on GitHub
- Updated for Kotlin 1.5
Books provide a structured way to gain expertise in Kotlin at your own pace. I recommend picking one suitable to your experience level and areas of interest be it Android, backend or multiplatform development.
Best Video Tutorials to Learn Kotlin
For quick and free learning, video tutorials on YouTube and other platforms are quite helpful:
Kotlin Course – FreeCodeCamp
FreeCodeCamp‘s 8 hour Kotlin tutorial covers all key concepts starting from basics like variables and functions to advanced topics including DSLs, sequences, destructuring etc.
Kotlin Tutorial – Programming with Mosh
Mosh Hamedani explains Kotlin fundamentals clearly while showing how to build a desktop TODO app. The 4.5 hour course is project-focused making concepts stick.
Kotlin Crash Course
Brad Traversy‘s fast-paced 1.5 hour Kotlin introduction covers a lot of ground including syntax, OOP, collections, lambdas, null safety etc.
Learn Kotlin for Beginners
In this 3.5 hour tutorial, Jason Fedin shows how to build a complete Snake game clone while covering all Kotlin basics along the way.
Kotlin Course – FreeCodeCamp
FreeCodeCamp‘s YouTube course is one of the most comprehensive video tutorials for mastering Kotlin fundamentals and advanced concepts like DSLs, coroutines etc.
These free tutorials on YouTube deliver engaging hands-on learning. Do subscribe to channels like FreeCodeCamp, Google Developers, Java Brains etc. for more Kotlin content.
Online Courses Comparison
Here is a quick overview of popular paid Kotlin courses:
| Course | Duration | Highlights |
|---|---|---|
| Complete Kotlin Developer | 30 hrs | Comprehensive. Build projects. |
| Kotlin for Java Developers | 8 hrs | Concise. Interactive. |
| Android 12 & Kotlin | 47 hrs | Advanced Android development. |
| Kotlin Bootcamp | 12 hrs | Project-based. Free 7-day trial. |
| Functional Kotlin | 6 hrs | Functional programming focus. |
The Kotlin for Java Developers course on Educative stands out for its concise and interactive delivery. But do choose based on your skill level, project needs and focus areas like Android, backend or web development.
Learn by Coding: Hands-on Practice
After going through courses, books and tutorials, it‘s vital to practice your Kotlin skills through coding exercises:
- Solve programming challenges on Codewars and Exercism
- Attempt Katas on Kotlin Koans
- Build projects on JetBrains Academy – free 7-day trial
- Practice code snippets on Kotlin Playground
- Solve computational problems on Project Euler using Kotlin
Hands-on practice is vital for reinforcing concepts learned and developing proficiency in applying Kotlin for real-world tasks.
So do invest time into doing small coding exercises, solving programming challenges, building projects etc. after going through courses and tutorials.
Key Takeaways
Let‘s summarise the key points:
- Kotlin is the ideal language for Android development with over 71% market share
- It offers null safety, functional programming capabilities and excellent Java interop
- Start with Kotlin basics by taking concise courses like Kotlin Bootcamp for Programmers and others
- For in-depth learning, comprehensive courses by Udemy, Educative, JetBrains etc. are valuable
- Kotlin books like Kotlin in Action provide structured and detailed coverage
- Video tutorials on YouTube channels like FreeCodeCamp offer free learning
- Gain proficiency by hands-on practice on Codewars, Kotlin Koans, JetBrains Academy etc.
By spending 5-10 hours per week on these resources over a few months, you can become extremely proficient in Kotlin.
If you are an experienced Java or Android developer, the transition to Kotlin will be relatively smooth. But even for beginners, Kotlin provides a simple and intuitive starting point.
I highly recommend investing time into learning Kotlin in 2025 to boost your skills and ‘future proof‘ your career as a mobile developer.
