Setting Up a Kotlin Project

Tools you will use

IntelliJ IDEA (by JetBrains) and Android Studio (built on it) have the best Kotlin support. Most projects build with Gradle, and the Gradle Kotlin DSL (build.gradle.kts) lets you write build scripts in Kotlin with IDE completion. Maven is also supported. For quick experiments you can use the command-line compiler kotlinc, Kotlin scratch files in the IDE, or the online Kotlin Playground. Plugin and library versions change often, so check the docs for your version.

A minimal Gradle Kotlin DSL build

build.gradle.kts for a JVM application (versions are examples).

plugins {
    kotlin("jvm") version "2.0.21"   // check the docs for the current version
    application
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation(kotlin("test"))
}

kotlin {
    jvmToolchain(17)
}

application {
    mainClass.set("MainKt")   // top-level main in Main.kt compiles to class MainKt
}

Use the Gradle wrapper

Commit gradlew and the wrapper files so every developer and CI machine uses the same Gradle version; run ./gradlew run or ./gradlew test instead of a globally installed Gradle.

Quick check: What is `build.gradle.kts`?

• A Gradle build script written in the Kotlin DSL
• A compiled Kotlin library
• An Android manifest
• A ktlint configuration file