Kotlin 2026: The Mega Course – All-in-One

Name: Kotlin 2026: The Mega Course – All-in-One
Rating: 4.6 (120 reviews)

From Zero to Job-Ready Kotlin Developer | The World’s Most Comprehensive Program

Created byAndrey Sumin

Last updated 6/2026

English

English [Auto],Spanish [Auto],

What you'll learn

Programming fundamentals
Object-oriented programming
Design patterns
Functional programming
Coroutines & Flow
Multithreading and asynchronous programming
Collections under the hood: ArrayList, LinkedList, HashMap, HashSet, TreeSet; algorithmic complexity of operations
Advanced Kotlin: invariance/covariance/contravariance; inline/noinline/crossinline; reified, etc.
Building complex software systems
Interview preparation
Networking
File I/O & serialization

Course content

9 sections • 167 lectures • 37h 1m total length

What is programming?3:10
Why do we need programming languages?4:22

Downloading the development environment4:19
First program11:31
Reading from the console. Variables14:59
Special characters and templates9:39
Integer type Int13:44
Integer division7:43
Conditional operator11:11
Conditional operator. Part 2. Combining19:18
Mutable variables12:43
Floating-point numbers15:40
Introduction to collections12:03
Repeat and While loops18:16
For loop and the size property14:37
Ranges8:04
Integer types Long, Short, Byte12:55
If and when are expressions16:40
Character data type15:55
Master the char data type in Kotlin, using single quotes. Explore ascii codes and print A to Z with loops and ranges, using isLetter and isDigit for password validation.
Do-while and split10:13

Introduction to OOP5:39
Discover the fundamentals of object oriented programming by learning how classes describe data types like int, and how objects or instances realize those classes in code.
Creating a class and an object18:42
Introduction to functions8:32
Functions with parameters10:42
Explore functions with parameters by declaring names and types, passing single or multiple arguments, and printing each action step via a coffee assistant example.
The keyword this and named parameters21:20
Introduction to constructors12:31
Constructor overloading13:55
Primary constructor12:31
Return type of functions17:22
Introduction to inheritance19:09
Upcast, Downcast, Smartcast10:39
Introduction to polymorphism13:54
Practice: creating an accountant. The super method27:12
Enum23:41
Working with files and mutable collections23:36
Manual serialization and deserialization17:04
Removing elements from a list21:30
Refactoring10:04
Examination26:07
Encapsulation and access modifiers15:33
Abstract classes13:21
Interfaces24:27
The Any class and the toString method9:52
OOP overview5:55

Getters and setters. Part 120:17
Getters and setters. Part 214:43
Single Responsibility Principle14:10
Refactoring and StringBuilder21:43
Singleton Object8:50
Backing Field12:45
The copy method13:48
The equals method15:07
The hashCode method. Set collections19:57
Data Classes14:11
Additional notes on the copy method5:20
Explore how Kotlin's data class copy method works, its generated parameters, and how overloading and parent-child method signatures prevent conflicts while enabling object copying with all four fields.
Nullable Types12:44
Elvis and Unit7:22
Try catch15:23
Explore exceptions in Kotlin by building and throwing arithmetic and number format exceptions, and master try catch blocks to gracefully handle division by zero and invalid input.
Nothing11:25

Kotlin Serialization23:31
Getting test data20:00
Pure functions7:07
Anonymous classes20:35
Lambda expressions13:37
Introduction to Generics14:10
Extension functions13:25
Inline functions15:50
Examples of higher-order functions9:06
The let function14:37
The also function10:03
Link to the official documentation on scope functions https://kotlinlang.org/docs/scope-functions.html
Map collections20:46
Explore Kotlin map collections by deserializing a json dictionary into entry objects, using immutable and mutable maps for fast lookups, and implementing a phonebook example.
Map for performance improvement6:30
The With and Apply functions15:49
The Run function and Method reference6:45

Basics of multithreading15:06
Master basics of multithreading in Kotlin and explore design patterns by moving from a single-threaded example to concurrent execution with thread, runnable, lambda, and Kotlin concurrent thread.
Singleton. Companion. Init.23:20
Singleton. Implementation methods13:27
Singleton. Synchronization17:08
Creating a GUI15:38
Observer. Introduction23:47
Observer. Dependency on abstractions13:19
Observer. Functional interface9:33
Observer. Observable interface13:37
Observer. MutableObservable16:31
Observer. Backing field and summary6:15
Command and BlockingQueue19:18
Sealed Interface16:48
Builder12:48

Junit Part 117:10
Junit Part 2. Parameterized Test13:03
Dependency for the junit library:
testImplementation("org.junit.jupiter:junit-jupiter-params:5.11.3")
Arrays20:13
ArrayList. Part 112:37
ArrayList. Part 214:52
ArrayList. Part 3. Constants and operators12:08
Algorithmic complexity10:46
Testing exceptions. System.arraycopy15:52
Implement index bounds checks and index out-of-bounds exceptions in a Kotlin array list, and optimize element shifting with system array copy.
LinkedList. How it works6:24
LinkedList. Implementation27:13
LinkedList. Doubly linked list20:22
HashSet. How it works8:47
HashSet. Implementation. Part 123:16
HashSet. Implementation. Part 214:50
HashSet. Interview questions21:45
Parameterized collections8:53
Collections and Iterable22:09
MutableIterable8:44
Set implementations9:56
TreeSet structure4:17
Immutable collections13:17
Map collections21:20
Using Map inside Set12:15
Collections interview12:04
Interview presentation:

Creating a GUI8:52
Adding logic and the String.format method13:40
Show minutes and seconds in a timer, padded with zeros using String.format. Use an action listener for button clicks and simulate loading a book and author to illustrate async patterns.
Callback mechanism9:44
Learn how to use the callback mechanism to run long operations on a background thread, keep the user interface responsive, and avoid blocking, while understanding callback hell and coroutines.
Suspend functions12:00
Coroutines under the hood13:00
Executor Services12:11
Structured Concurrency. Part 111:19
Dispatchers Default and Unconfined10:23
Dispatchers IO and Main5:46
Job and parallelism10:06
Async and Deferred6:46
Jobs Hierarchy16:57
Exceptions. Part 110:57
Exceptions. Part 2. Async12:14
Coroutine cancellation10:42
Suspend Coroutine8:36
SupervisorJob5:11
What are data streams10:55
Ways to create a Sequence8:17
Getting started with Flow14:36
Introduction to API12:31
Loading data from the network20:38
Creating a GUI and working with Regex17:51
Reactive style16:35
Channels and Debounce10:15
Cold data streams9:02
Hot data streams10:34
ShareIn9:08
Buffer and Backpressure12:22
Screen state as Flow13:13
MutableStateFlow8:17
SharedFlow vs StateFlow14:00
Exceptions in Flow10:44
Exception handling practice7:22
The FlowOn operator8:32
CoroutineScope inheritance11:24
Coroutine synchronization11:02
Channels11:04

Invariance and covariance17:55
Project where we worked with collections:
Contravariance12:04
Type erasure6:53
Reified and Star Projection11:31
Inline and Non-local return13:37
Crossinline and noinline9:40
Value classes7:04
Property delegation21:48
Interface implementation delegation12:43
Inner and nested classes6:05
Clarify inner versus nested classes in Kotlin, including anonymous inner classes and how they access outer properties. See concise examples with a display class, text field, button, and action listener.
Destructuring declaration and infix11:40
Memory structure in Kotlin10:45
How programs in Java and Kotlin work4:54
The internal modifier9:54
Interview27:06
Interview presentation:
Final1:37
Bonus Lecture0:28

Requirements

No prior knowledge is required. We’ll cover everything you need from the very basics and go through every step together. You’ll just need a computer and internet access — we’ll install and set up everything else during the course.

Description

Hello everyone, and welcome to the Complete Kotlin Course: Zero to Job-Ready!

My name is Andrey Sumin.

This course is for anyone who wants to learn Kotlin—a modern language used to build Android apps, create server-side applications, and work on multiplatform projects. It’s designed so you can start from scratch, even with no prior programming experience. Not just the basics—we’ll dive into the language’s nuances and practice hands-on, so by the end you’ll be fully prepared for a Kotlin interview. Throughout the course, you’ll complete practical assignments and projects that reinforce each topic and help you build real development skills.

I wish you success in mastering Kotlin—may you gain new knowledge and the inspiration to conquer the world of programming! See you in the course!

Why Kotlin?
Because it’s a modern language with official support from Google. Designed with lessons from dozens of other languages, Kotlin keeps the best practices and removes unnecessary complexity. Code is shorter and clearer, and writing in Kotlin is fast and convenient. Built-in null-safety and a modern concurrency model with coroutines improve application stability and safety. Plus, it’s fully compatible with Java and the JVM ecosystem, so you can leverage existing libraries and familiar tools without extra hurdles. Most importantly, Kotlin has strong prospects: active development, broad industry support, and high market demand.

Who this course is for:

This course is suitable for anyone who wants to learn to program in Kotlin.
If you have no programming experience, you’ll find everything you need here to pursue a new career.
If you’ve already written programs in Kotlin or any other language, you’ll find plenty of valuable material and be able to deepen your knowledge.

Kotlin 2026: The Mega Course – All-in-One

What you'll learn

Explore related topics

Course content

Introduction2 lectures • 8min

Basic syntax18 lectures • 3hr 50min

Object-Oriented Programming24 lectures • 6hr 23min

Diving into Kotlin15 lectures • 3hr 28min

Functional programming15 lectures • 3hr 32min

Design patterns14 lectures • 3hr 37min

Structure of collections24 lectures • 5hr 52min

Asynchrony and multithreading38 lectures • 7hr 7min

Kotlin in detail17 lectures • 3hr 6min

Requirements

Description

Who this course is for: