Kotlin Handbook

Learn Through Practice

Image presents a Kotlin Course box mockup for "Kotlin Handbook. Learn Through Practice"

Explore Kotlin essentials with practical code examples, engaging exercises, and interactive quizzes. Straight to the point!

Image presents a Kotlin Course box mockup for "Kotlin Handbook. Learn Through Practice"

Piotr’s just like a super friendly guy who’s really passionate about these topics that he’s teaching. He’s really good at distilling these topics down into a very clear explanation of the underlying tools and technologies.

I strongly recommend these course of Kotlin to everybody who is interested in learning to code, people like Piotr are out there creating learning resources for all of us.

Thanks to codersee what taught me real world concepts which I use in my day to day job.

Geovanny Mendoza








quiz Questions

Does This Sound Familiar?

So, I Have Something
For You

🔥 Course "Kotlin Handbook. Learn Through Practice"

Who is this course for?

Here's What You Will Find Inside:

Course Curriculum


Welcome To The Course!

Course Structure & Setup

Basic Types & Variables

Variables & Constants

Data Types

Type Inference and Explicit Typing

Variables Scopes & Lifetime

String Manipulation

Types Conversion

Nullable Types and Operators

Operators & Expressions

Arithmetic, Unary & Assignment Operators

Comparison & Logical Operators

Bitwise Operators and Operator Precedence

Control Flow Statements

Conditional Statements Introduction

Exploring The When Expression

Advanced When Expressions and Smart Casts

Nested Control Flow Statements

Basic Loops

Basic Loop Structures

Break, Continue & Labels



Lists, Sets & Maps

Looping Over Collections

Collections Functions Part 1

Collections Functions Part 2


Functions & Recursion

Functions Introduction

Visibility Modifiers and Local Functions

Extension Functions

Lambda Expressions

Inline & Infix Functions

Recursion & Tail Recursion

Scope Functions

Classes, Objects & Inheritance Part 1

Classes & Objects Introduction

Visibility Modifiers, Custom Getters and Setters


Abstract Classes & Interfaces

Object Equality & Hash Code

Data Classes, Sealed Classes & Enum Classes

Classes, Objects & Inheritance Part 2

Object Declarations, Object Expressions & Companion Objects

Nested & Inner Classes


Operator Overloading



Interfaces, Classes, Properties & Functions

in, out, *

Type Erasure & Reified Types



Function Literals with Receiver

Type-Safe Builders

Scope Control With @DslMarker


Introduction To Exceptions & Exceptions Handling

Custom Exceptions & Hierarchy

Input & Output (I/O)

Reading User Input

Introduction To File Handling

Reading Data From Files

Writing Data To Files

Annotations & Reflection

Introduction To Reflection


Custom Annotations & Targets

Use-Site Targets, Retention & Repeatable Annotations

Unit Testing


Writing Testable Code

Kotlin Test Frameworks & Libraries

Testing With JUnit

@BeforeAll & @BeforeEach

Parametrized Tests

Mocking With Mockk


Final Exercise

Time To Say Goodbye

Certificate Of Completion

Image presents an example certificate of completion for Kotlin course.

Who Am I?

My name is Piotr Wolak, and I am a software engineer and teacher at heart.

I specialize in Kotlin and backend development, and I’ve decided to create Codersee to share my knowledge in this area through practical, step-by-step articles, tutorials, and courses.

My mission is to help people learn and grow their skills in the areas of Kotlin and backend development.

I believe that the best way to truly understand a subject is to put it into practice. That’s why I focus on providing practical examples and hands-on exercises in my content.

Let’s work together and grow together!

Image presents a photo of Piotr Wolak - founder of Codersee and instructor of the course.


Once you buy a course, you get lifetime access to it. Learn whenever you want and on all devices you own.

Moreover, you will still have access to the course after you complete it. This way, you can revisit topics and refresh your memory through exercises and quizzes. 

No, the course consists of pragmatic, written lessons. 

This approach combined together with frequent exercises and summary quizzes helps increase your focus time. 

Yes, the course is continuously updated, and it’s an open project where new bonuses are added.

Kotlin programming language continuously evolves and you don’t have to worry that this course becomes legacy at some point. 

Yes, we have a dedicated closed Facebook group.

This way, you can get to know other participants, ask additional questions, and exchange your knowledge and skills. 

Enroll In Course ✅

Course Access

Until 15th May
$ 14
  • Lifetime Course Access

Course Access

From 15th May
$ 24
  • Lifetime Course Access

Course & Tutoring Bundle

$ 249
  • Lifetime Course Access
  • 3 Hours Of 1:1 Tutoring

To make Codersee work, we log user data. By using our site, you agree to our Privacy Policy and Terms of Use.