Basic scala/swing HelloWorld application with gradle

build.gradle

plugins {
    id 'scala'
    id 'com.github.johnrengelman.shadow' version '1.2.3'
}

repositories {
    mavenCentral()
}

dependencies {
    compile 'org.scala-lang:scala-library-all:2.11.5'
    compile 'org.scala-lang.modules:scala-swing_2.11:1.0.1'
}

def mainClassName = 'cz.khardix.scala.HelloWorld'

jar.manifest.attributes 'Main-Class': mainClassName

task run(type: JavaExec, dependsOn: classes) {
    main = mainClassName
    classpath sourceSets.main.runtimeClasspath
    classpath configurations.runtime
}

HelloWorld.scala

package cz.khardix.scala

import swing._

object HelloWorld extends SimpleSwingApplication {
  def top = new MainFrame {
    title = "Hello World!"

    contents = new Button {
      text = "Click Me!"
    }
  }
}