Free & Open Source
Kotlin Crash Course
A hands-on, chapter-by-chapter guide for JavaScript and Python developers who want to build Android apps with Kotlin.
Start Learning →7
Chapters
2.5h
Est. Time
0
Dependencies
Chapter 1
15 min
Basics & Types
Variables, constants, type inference, strings, and basic operators.
Chapter 2
20 min
Functions
Default arguments, named parameters, lambdas, and higher-order functions.
Chapter 3
20 min
Null Safety
Nullable types, safe calls, Elvis operator, and smart casts.
Chapter 4
20 min
Collections
Lists, sets, maps, and functional operations like map, filter, reduce.
Chapter 5
25 min
Classes & OOP
Data classes, sealed classes, inheritance, and extension functions.
Chapter 6
25 min
Coroutines
Async programming without callback hell. suspend, launch, async, Flow.
Chapter 7
25 min
Android & Compose
Jetpack Compose, ViewModel, StateFlow, and modern Android UI.
How to use this course: Each chapter builds on the previous one. Read the explanation, study the examples, try the exercises, and pass the concept check before moving on. Use the ← → arrow keys to navigate between chapters.
Prerequisites
- You know JavaScript or Python (we compare syntax throughout)
- You understand basic programming: variables, loops, conditionals
- You want to build Android apps (or learn Kotlin for any platform)
Tools You'll Need
- Android Studio — developer.android.com/studio
- Kotlin Playground — play.kotlinlang.org for quick experiments