Getting Started

Kotlin Introduction

Learn Kotlin — the modern, concise language that is now Google's preferred language for Android.

What is Kotlin?

Kotlin is a modern, statically typed programming language developed by JetBrains. It runs on the Java Virtual Machine (JVM) and is fully interoperable with Java. Google announced Kotlin as the preferred language for Android development in 2019.

Why Kotlin?

Concise: Reduces boilerplate by up to 40% compared to Java
Safe: Null safety built into the type system
Interoperable: 100% Java interoperability
Versatile: JVM, Android, JavaScript, Native (multiplatform)
Modern: Coroutines, extension functions, data classes, sealed classes

Kotlin vs Java

Kotlin compiles to the same JVM bytecode as Java but with:

Much less verbosity
Null safety by default
Functional programming features
No checked exceptions

Example

kotlin

// Kotlin is concise
fun main() {
    println("Hello, Kotlin!")

    // val = immutable (like final in Java)
    val name = "Kotlin"

    // var = mutable
    var version = 1.9

    // Type annotation (optional when inferred)
    val language: String = "Kotlin"
    var count: Int = 0

    // String templates
    println("Hello from $name $version!")
    println("Length: ${name.length}")

    // Multi-line string
    val text = """
        |Line 1
        |Line 2
        |Line 3
    """.trimMargin()
    println(text)
}

Try It Yourself