Introduction to Kotlin & Setup

🎯 Goal: Understand what Kotlin is, why it’s used, and set up your environment to start coding.

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What is Kotlin?

Kotlin is a modern, concise, and expressive programming language developed by JetBrains. It is:
✅ Statically typed (type safety at compile time).
✅ Interoperable with Java (can use existing Java libraries).
✅ Concise & expressive (less boilerplate code than Java).
✅ Null-safe (helps avoid NullPointerException).
✅ Functional & Object-Oriented (supports both paradigms).

Primary Uses of Kotlin:

• General-purpose backend development.
• Android development (but in this series we’re focusing on Kotlin only, not Android).
• Scripting and command-line tools.
• Kotlin/Native for cross-platform development.

Setting Up Kotlin

You have multiple ways to write and run Kotlin code:

Option 1: JetBrains Playground (Recommended for Quick Testing)

🚀 Website: https://play.kotlinlang.org

• No installation required — just start coding in your browser.

Option 2: IntelliJ IDEA (Recommended for Long-Term Learning)

1️⃣ Download IntelliJ IDEA (Community Edition) → https://www.jetbrains.com/idea/download
2️⃣ Install and open IntelliJ IDEA.
3️⃣ Create a new Kotlin project → Select Kotlin/JVM.
4️⃣ Write your first Kotlin program inside src/main/kotlin/Main.kt

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Option 3: Command Line (For Minimal Setup)

1️⃣ Install Kotlin:

• macOS (via Homebrew): brew install kotlin
• Windows/Linux: Use Kotlin Compiler

2️⃣ Run Kotlin:

• Create a file main.kt, write your Kotlin code, and run:

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

Writing Your First Kotlin Program

Hello, World!

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

Explanation:

• fun main() → The main function, the entry point of the program.
• println() → Prints text to the console.

Running Your Code

• In IntelliJ IDEA: Click the green play button ▶️.
• In JetBrains Playground: Click “Run”.

Understanding the Kotlin Compiler & REPL

🔹 Kotlin Compiler:

• Converts Kotlin code to Java bytecode (.class files) and runs it on the JVM.

🔹 Kotlin REPL (Read-Eval-Print Loop):

• Allows you to execute Kotlin statements interactively.
• Open it in IntelliJ IDEA → Tools→ Kotlin → Kotlin REPL
• Example:

>>> 5 + 3
8
>>> "Kotlin".length
6

⭐ Next Up: Variables & Data Types

🔎 Click “Learn Kotlin in 30 Days” to see all articles

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