Kotlin Dagger Example

coffee.kt

import dagger.Component
import dagger.Module
import dagger.Provides
import javax.inject.Inject
import javax.inject.Singleton

interface Heater {
  fun on()
  fun off()
}

interface Pump {
  fun pump()
}

@Module
class PumpModule {
  @Provides fun providePump(): Pump = object : Pump {
    override fun pump() = println("=> => pumping => =>")
  }
}

@Module(includes = arrayOf(PumpModule::class))
class DripCoffeeModule() {
  @Provides fun provideHeater(): Heater = object : Heater {
    override fun on() = println("~ ~ ~ heating ~ ~ ~")
    override fun off() {}
  }
}

class CoffeeMaker
@Inject constructor(val heater: dagger.Lazy<Heater>,
                    val pump: Pump) {
  init {
    heater.get().on()
    pump.pump()
    println(" [_]P coffee! [_]P")
    heater.get().off()
  }
}

@Singleton
@Component(modules = arrayOf(DripCoffeeModule::class))
interface CoffeeShop {
  fun maker(): CoffeeMaker
}

fun main(args: Array<String>) {
  val coffeeShop = DaggerCoffeeShop.create()
  coffeeShop.maker()
}

gradle.build

buildscript {
  ext {
    kotlinVersion = '1.0.0-beta-2423'
    daggerVersion = '2.0.2'
  }
  repositories {
    jcenter()
  }
  dependencies {
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
  }
}

apply plugin: 'kotlin'

repositories {
  jcenter()
}

kapt {
  generateStubs = true
}

dependencies {
  kapt "com.google.dagger:dagger-compiler:$daggerVersion"
  compile "com.google.dagger:dagger:$daggerVersion"
  compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
}

sourceSets {
  main.java.srcDirs += 'src/main/kotlin'
}