Kotlin Setup

To write and run Kotlin programs, you need a few tools installed on your computer. This topic walks you through two paths: using IntelliJ IDEA (recommended for beginners) and using the command line.

What You Need

• JDK (Java Development Kit) – Kotlin runs on the JVM, so JDK must be installed first.
• IntelliJ IDEA – The best editor for Kotlin, made by the same company that created Kotlin.

Step 1: Install the JDK

The JDK lets your computer understand and run Java and Kotlin bytecode.

1. Visit adoptium.net or oracle.com/java.
2. Download JDK 17 or later (LTS version recommended).
3. Run the installer and follow the prompts.
4. Verify the installation by opening a terminal and typing:

java -version

You should see output like: java version "17.0.x"

Step 2: Install IntelliJ IDEA

1. Visit jetbrains.com/idea.
2. Download the Community Edition — it is free and includes Kotlin support.
3. Install it like any other application on your operating system.
4. Open IntelliJ IDEA after installation.

Step 3: Create Your First Kotlin Project

Setup Flow Diagram:

  Open IntelliJ IDEA
         │
         ▼
  Click "New Project"
         │
         ▼
  Select "Kotlin" as language
         │
         ▼
  Select "JVM" as build target
         │
         ▼
  Choose a project name and location
         │
         ▼
  Click "Create"
         │
         ▼
  Project opens with src/main/kotlin folder

IntelliJ creates a project structure automatically. Your Kotlin files go inside the src/main/kotlin folder.

Step 4: Verify Kotlin Is Working

Right-click on the kotlin folder, select New → Kotlin File/Class, and name it Main. Add this code:

fun main() {
    println("Kotlin is ready!")
}

Click the green play button at the top of the editor. The output panel at the bottom shows:

Kotlin is ready!

Alternative: Online Kotlin Playground

If you do not want to install anything yet, use the official Kotlin playground at play.kotlinlang.org. Type code in your browser and run it instantly. This works for learning, but you will need a local setup for real projects.

Alternative: Command Line Setup

Developers who prefer the terminal can install the Kotlin compiler directly.

Install via SDKMAN (Linux/Mac)

sdk install kotlin

Install via Homebrew (Mac)

brew install kotlin

Verify Installation

kotlin -version

Compile and Run a File

kotlinc Main.kt -include-runtime -d main.jar
java -jar main.jar

Project Folder Structure

MyKotlinProject/
├── src/
│   └── main/
│       └── kotlin/
│           └── Main.kt       ← Your Kotlin files go here
├── build.gradle.kts           ← Build configuration
└── settings.gradle.kts        ← Project settings

You only need to work inside the kotlin folder for now. The build files handle compilation automatically when you press the run button in IntelliJ.