Kotlin Tutorials

Learn Kotlin,
step by step.

Clear explanations, real code examples and sample output — from basics to coroutines, OOP and JVM interop.

coroutine.kt

launch {
 val data = fetchData()
 println(data)
}

main.kt

fun main() {
 val greeting = "Hello, Kotlin!"
 println(greeting)
}

data.kt

data class User(val name: String)
val user = User("Kotlin")

Start with Basics Browse all topics

214+

Tutorials

Tracks

Topics

JVM

Platform

Kotlin Basics

Everything you need to start writing Kotlin - from your first program to functions, with examples and output for every concept.

55 articles View all topics

Basic Programs Get started with Kotlin: your first program, variables, and comments. 4 tutorials Kotlin Data Types Explore Int, Float, Double, Char, Boolean, String and more, with type conversion. 11 tutorials Kotlin Operators Arithmetic, relational, logical, assignment and Kotlin's special operators. 15 tutorials Conditional Statements Control program flow with if, when, break, continue and return. 4 tutorials Kotlin Input and Output Read input and print output in Kotlin, including the Scanner class. 5 tutorials Looping & Controls Repeat work with for, while, do-while and the repeat function. 6 tutorials Kotlin Functions Define functions with default, named and vararg parameters, single-expression, local, tailrec and infix functions. 10 tutorials

Kotlin Intermediate

Move beyond basics with null safety, strings, arrays, collections, packages and exception handling.

37 articles View all topics

Null Safety Nullable types, safe casts, let, lateinit and null handling in Kotlin. 7 tutorials Kotlin Strings String basics, templates, comparison, substring and raw strings. 6 tutorials Kotlin Arrays Declare, initialize, access and iterate arrays in Kotlin. 5 tutorials Collections Intro Lists, sets, maps and common collection operations. 6 tutorials Packages & Imports Organize code with packages, imports and visibility modifiers. 5 tutorials Exception Handling try-catch, finally, throw, custom exceptions and try expressions. 6 tutorials Type Features Type aliases, destructuring declarations and related Kotlin type syntax. 2 tutorials

Object Oriented Kotlin

Classes, inheritance, interfaces, data classes, objects and sealed classes with examples.

31 articles View all topics

Kotlin Classes Declare classes, properties, constructors and init blocks. 8 tutorials Inheritance Open classes, overriding, abstract classes and inheritance rules. 5 tutorials Interfaces Define and implement interfaces, functional interfaces and properties. 5 tutorials Data Classes Data class declaration, copy, destructuring and equals/hashCode. 4 tutorials Objects & Enums Object declarations, companion objects, expressions and enum classes. 5 tutorials Sealed Classes Sealed classes, when expressions and restricted type hierarchies. 4 tutorials

Functional Kotlin

Lambdas, higher-order functions, scope functions, delegates and generics.

26 articles View all topics

Lambda Expressions Lambda syntax, parameters, return values and anonymous functions. 5 tutorials Higher Order Functions Functions as parameters, inline functions and return types. 5 tutorials Scope Functions let, run, with, apply and also scope functions explained. 5 tutorials Delegates Property delegates, lazy, observable and class delegation. 5 tutorials Generics Generic functions, classes, constraints, variance and star projection. 5 tutorials Extension Functions Add new behaviour to existing types with Kotlin extension functions and properties. 1 tutorials

Standard Library

Lists, maps, sets, sequences, ranges, regex and file I/O in Kotlin.

26 articles View all topics

List, Map & Set Immutable and mutable collection operations, filtering and sorting. 6 tutorials Sequences Lazy sequences, operations and when to use sequences vs lists. 5 tutorials Ranges Range expressions, until, downTo and step in Kotlin. 4 tutorials Regular Expressions Regex matching, find, replace and common patterns in Kotlin. 5 tutorials File I/O Read and write files, lines and path operations in Kotlin. 6 tutorials

Kotlin Coroutines

Asynchronous programming with coroutines, dispatchers, async and Flow.

24 articles View all topics

Coroutine Basics Introduction, suspend functions, launch, runBlocking and coroutine scope. 6 tutorials Dispatchers Main, IO, Default dispatchers and withContext for thread switching. 5 tutorials Async & Await async builder, await, parallel work and exception handling. 5 tutorials Kotlin Flow Cold flows, operators, StateFlow and SharedFlow basics. 6 tutorials Advanced Coroutines Coroutine cancellation, channels and producer-consumer patterns. 2 tutorials

JVM & Interop

Java interoperability, annotations and reflection on the JVM.

15 articles View all topics

Java Interop Call Java from Kotlin and Kotlin from Java with null safety and SAM. 6 tutorials Annotations Declare and use annotations, targets and retention in Kotlin. 5 tutorials Reflection Class, function and property references in Kotlin. 4 tutorials

Network

More learning sites

Explore tutorials on the main hub and dedicated language subdomains.

Main Hub Open site → C Programming Open site → C++ Open site → Java Programs Open site → AI Learning Hub Open site →

Connect

Also visit

LinkedIn Professional profile & updates @thiyagaraaj WIZIONTECH.COM Mobile and web development solutions Visit site Android Apps Free offline programming tutorials on Google Play View all apps

Learn Kotlin, step by step.

Learn Kotlin,
step by step.