Kotlin Get Started

Tools

• IntelliJ IDEA (or Android Studio for Android) is the main IDE; it bundles the Kotlin compiler.
• Gradle builds Kotlin projects; the build script itself is usually written in Kotlin (build.gradle.kts).
• The command-line compiler kotlinc is handy for single files. You need a JDK (17 or newer) installed.

kotlinc hello.kt -include-runtime -d hello.jar   # compile to a runnable jar
java -jar hello.jar

A Gradle project

gradle init (choose application, Kotlin) creates app/src/main/kotlin/App.kt and a build file:

plugins {
    kotlin("jvm") version "2.4.21"
    application
}

application { mainClass = "AppKt" }

./gradlew run compiles and runs it. The program inside is plain Kotlin:

fun main() {
    println("Hello from my first Kotlin project!")
}

Hello from my first Kotlin project!