Environment Setup

This guide covers setting up Kotlin for command-line development on Windows, macOS, and Linux. For IDE-based development (recommended for beginners), see the next section.

Prerequisites

Before installing Kotlin:

1. Install JDK 8 or later

• ✅ Kotlin runs on the JVM, so you need Java Development Kit (JDK) version 8 or higher
• ✅ Download from Oracle or OpenJDK

1. Verify Java Installation

java -version

You should see output like:

java version "1.8.0_xxx" or higher

Installing Kotlin Compiler

Method 1: Using SDKMAN! (Recommended for macOS/Linux)

SDKMAN! is a tool for managing parallel versions of multiple SDKs.

Step 1: Install SDKMAN!

curl -s "https://get.sdkman.io" | bash
source "$HOME/.sdkman/bin/sdkman-init.sh"

Step 2: Install Kotlin

sdk install kotlin

Step 3: Verify Installation

kotlin -version

Method 2: Using Homebrew (macOS)

Step 1: Install Homebrew (if not already installed)

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Step 2: Install Kotlin

brew install kotlin

Step 3: Verify Installation

kotlin -version

Method 3: Manual Installation (Windows/macOS/Linux)

Step 1: Download Kotlin Compiler

• ✅ Visit Kotlin GitHub Releases
• ✅ Download the latest kotlin-compiler-X.X.X.zip file

Step 2: Extract the Archive

• ✅ Windows: Extract to C:\kotlin (or any preferred location)
• ✅ macOS/Linux: Extract to /usr/local/kotlin or ~/kotlin

Step 3: Set Environment Variables

Windows

1. Open System Properties → Environment Variables
2. Under System Variables, find Path and click Edit
3. Click New and add: C:\kotlin\bin (or your extraction path)
4. Click OK to save

macOS/Linux

Add to your ~/.bashrc, ~/.zshrc, or ~/.bash_profile:

export PATH=$PATH:/usr/local/kotlin/bin

Reload the configuration:

source ~/.bashrc  # or ~/.zshrc

Step 4: Verify Installation

Open a new terminal and run:

kotlinc -version

Expected output:

info: kotlinc-jvm 1.9.x (JRE 1.8.x)

Writing Your First Kotlin Program

Step 1: Create a file named hello.kt

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

Step 2: Compile the Program

kotlinc hello.kt -include-runtime -d hello.jar

Explanation:

• ✅ kotlinc: Kotlin compiler
• ✅ hello.kt: Source file
• ✅ -include-runtime: Includes Kotlin runtime in the JAR
• ✅ -d hello.jar: Output JAR file name

Step 3: Run the Program

java -jar hello.jar

Output:

Hello, Kotlin!

Alternative: Using Kotlin Script (.kts)

Kotlin Script files can be run directly without compilation:

Step 1: Create hello.kts

println("Hello from Kotlin Script!")

Step 2: Run Directly

kotlinc -script hello.kts

Common Commands

Troubleshooting

Error: "kotlinc is not recognized"

• ✅ Verify Kotlin bin directory is in PATH
• ✅ Restart terminal after setting environment variables
• ✅ On Windows, check if path uses backslashes: C:\kotlin\bin

Error: "Could not find or load main class"

• ✅ Ensure you used -include-runtime flag when compiling
• ✅ Verify JAR file was created successfully

Slow Compilation

• ✅ First compilation is always slower (JVM warmup)
• ✅ Use Kotlin daemon for faster subsequent compilations:

kotlinc -daemon hello.kt

Next Steps

• ✅ For Beginners: Install IntelliJ IDEA or Android Studio for better development experience
• ✅ Try Online: Use Kotlin Playground to experiment without setup
• ✅ Learn Basics: Move on to variables, data types, and control flow