Kotlin Tutorial 1 — Introduction

5 min readDec 14, 2016

Welcome to the Kotlin Tutorial. This is the first written tutorial series on the Internet that covers all the key basics you will need to know about the Kotlin programming language. The main prerequisite for this tutorial is that you have a basic understanding of programming (already know one programming language — Python, Java, Java Script etc). Despite the tutorial being geared toward Python developers it doesn’t matter if you know a different programming language. Note that the tutorial assumes you will be doing Kotlin development on a PC running Linux Mint 18 (Main edition — 64 bit).

Throughout the series the following tools will be used:

Atom 1.12.5 (programmer’s text editor)
IntelliJ Community Edition 2016.3 (IDE)
Gnome Terminal (terminal emulator)
Kotlin 1.0.5–2 (programming language, includes tools like the compiler)
SDK Man

Kotlin is a pragmatic (industrial), statically typed, multi paradigm (procedural, OO, functional), and general purpose programming language created by Jet Brains in July 2011. The language was created with the aim to make it easier to develop software (of all sizes) that is easier to maintain, and quicker to develop (more productive). Often Kotlin will be used to develop server side (eg micro services), database, and mobile software (Android applications and libraries) as well as test software.

Can also find Kotlin being used to develop desktop applications, scripting for software, DSL’s (Domain Specific Languages), and to a lesser degree front end web applications / websites, even games (eg using libGDX). Jet Brains have plans to expand the use of Kotlin to developing embedded programs (most likely running on ARM micro-controllers without a garbage collector), however that is currently in the investigation phase.

Some of the major companies using Kotlin include the following:

Pinterest
Gradle
Basecamp (creator of Ruby on Rails)
American Express
Square
Jet Brains (uses Kotlin in various products including it’s flagship product IntelliJ)
Pivotal
3D Robotics
Expedia

Install Kotlin

Kotlin will be installed via SDK Man, which is a tool that allows software development tools to be easily installed/uninstalled (similar to Synaptic which is included in Linux Mint).

Open the terminal with Ctrl+Alt+t (keyboard shortcut)
Enter the following to install SDK Man: curl -s “https://get.sdkman.io" | bash
Close the terminal and open up a new one
Check that SDK Man is installed by running the following: sdk version
Install Kotlin by running the following: sdk install kotlin 1.0.5–2
When the “Do you want kotlin 1.0.5–2 to be set as default?” prompt appears enter in Y, then press Enter
Check that Kotlin is installed by running the following: which kotlinc

Install Atom

Atom is a simple programmer’s text editor that has support for a wide variety of programming languages via its extensive plug-in system and has built-in Git support.

Illustration 1: Atom with open Kotlin Script file

Open terminal
Change directory to ~/Desktop
Download the deb file by running the following: wget https://atom.io/download/deb
On the desktop double click on the deb file to install Atom
Exit the Package Installer
Close the terminal
Click on the Menu button to show the Applications Menu
In the search box enter in atom
Press Enter to start Atom

Setup Atom

Some plug-ins will need to be installed so that Atom supports Kotlin.

In Atom go to Edit → Preferences
Select the Install section
Install the following packages: file-icons, git-plus, language-kotlin, language-kotlin-ide, linter, linter-kotlin, script
Click the Themes button
Install the following package: dracula-theme
Select the Themes section
Change UI Theme to One Light
Change Syntax Theme to Dracula
Select the Core section
Under Send Telemetry to the Atom Team select Do not send any telemetry data
Select Editor section
Change Tab Length to 4
Change Tab Type to soft
Set Font Family to roboto
Set Font Size to 17
Close the Settings tab (Ctrl+w)
Exit Atom

First Steps

Open a terminal. What do you think will happen when kotlinc (Kotlin Compiler) is run in the terminal?

A) Compiler throws a Wobbly
B) Basic help information is displayed
C) A segmentation fault occurs (memory loss)
D) Enters an interactive REPL environment
E) Compiler enters a curses session

Correct answer is: Enters an interactive REPL environment.

*Illustration 2: Kotlin REPL environment*

Enter the Kotlin REPL by running kotlinc. Type the following Kotlin code into the REPL:

Press Enter to run the code. You should see numbers being outputted to the screen. Now type in the following code:

Again press Enter. You should now have something similar to the following:

*Illustration 3: Sample Kotlin REPL session*

As you can see the Kotlin REPL is very similar to the Python interactive session below:

*Illustration 4: Python 3 interactive session*

A more fully featured Kotlin REPL can be used in IntelliJ, below is a teaser:

*Illustration 5: Kotlin REPL in IntelliJ*

Conclusion

That concludes the tutorial introduction which will have you setup for part of the tutorial series. Next tutorial will look at Kotlin’s data types (including its approach to nulls) in Kotlin Tutorial 2 — Basic Data Types.