Declare

Use the Koin DSL to describe your components definitions

// Given some classes 
class Controller(val service: BusinessService) 
class BusinessService() 
// just declare it 
val myModule = module { 
  single { Controller(get()) } 
  single { BusinessService() }
} 

Start

Just run startKoin function in your application

fun main(vararg args: String) { 
  // start Koin!
  startKoin {
    // declare modules
    modules(myModule)
  }
} 

Inject Constructors

Instances are resolved from your modules

// Controller & BusinessService are declared in a module
class Controller(val service: BusinessService) { 
  
  fun hello() {
    // service is ready to use
    service.sayHello()
  }
} 

Easy for Android

Just inject into your Android classes

// Just inject in a simple Activity 
class MyActivity() : AppCompatActivity() {
  // inject BusinessService into property
  val service: BusinessService by inject()
}