LibGDX: Kotlin setup

In my previous post I wrote how to configure gradle files to increase build and open IDE speed. Those steps needs to be done if you want to configure kotlin in your libGDX project. Otherwise, you'll get really poor IDE responsiveness and even gradle daemon crashes. Assuming, that you've done all instructions from my previous post, here is the magic steps to use Kotlin. It's easy now:

1. Android Studio (AS) / IDEA -> Settings -> find by "plugin" -> Click "Jetbrains" -> find by "kotlin" -> install kotlin and kotlin for android (optional) plugins and click restart IDE to complete install plugin
2. Open core/src/main directory and create "kotlin" directory there. Recreate directories for your package, like they are in "java" directory. If your app's package is com.mycompany.mygame, then create directory com, open it, create mycompany and so on.
3. Return to IDE. You may try tools -> Kotlin -> Configure kotlin in project... or add bold lines to your core/build.gradle:


apply plugin: 'kotlin'

buildscript {
    ext {
        kotlin_version = '0.11.91.4'
        gdxVersion = '1.5.2'
        box2DLightsVersion = '1.3'
        ashleyVersion = '1.3.1'
        aiVersion = '1.4.0'
    }

    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}
repositories {
    mavenCentral()
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    compile "com.badlogicgames.gdx:gdx:$gdxVersion"
    compile "com.badlogicgames.gdx:gdx-box2d:$gdxVersion"
    compile "com.badlogicgames.box2dlights:box2dlights:$box2DLightsVersion"
    compile "com.badlogicgames.ashley:ashley:$ashleyVersion"
    compile "com.badlogicgames.gdx:gdx-ai:$aiVersion"
    compile "com.badlogicgames.gdx:gdx-freetype:$gdxVersion"
    compile "com.badlogicgames.gdx:gdx-bullet:$gdxVersion"
}
sourceSets {
    main.java.srcDirs += 'src/main/kotlin'
}

3. Now, you may write kotlin files or convert existing java files to kotlin automatically from IDE. kotlin plugin doesn't need java plugin - it successfully lives in a project with java code and compiles it too. As long, as you keep worlds separate: java files in main/java and kotlin in main/kotlin all is good. If you'll create class com.mycompany.mygame.BestEver in main/java and then create com.mycompany.mygame.BestEver in main/kotlin, you'll get Duplicate class compile error as it must be.

You may find core already converted in my example project https://github.com/Deepscorn/NewLibGDXProjectTemplate. Good luck and happy coding!