MVP Kotlin

BaseActivity.kt

abstract class BaseActivity<MODEL : BaseModel<Bundle>, VIEW : BaseView, out PRESENTER : BasePresenter<MODEL, VIEW>> : KoinActivity() {
  protected abstract val presenter: PRESENTER

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val arguments = (javaClass.genericSuperclass as ParameterizedType).actualTypeArguments
    val model = Class.forName(arguments.first().javaClass.toString().split(" ").last()).newInstance() 
    presenter.bind(model as MODEL, this as VIEW)
  }

  override fun onPostCreate(savedInstanceState: Bundle?) {
    super.onPostCreate(savedInstanceState)
    presenter.viewReady(first = savedInstanceState == null)
  }

  override fun onSaveInstanceState(outState: Bundle?) {
    super.onSaveInstanceState(outState)
    presenter.model.save(outState)
  }

  override fun onDestroy() {
    super.onDestroy()
    presenter.unbind()
  }
}

BaseModel.kt

open class BaseModel<in TYPE> {
  open fun load(from: TYPE?) {}
  open fun save(to: TYPE?) {}
}

BasePresenter.kt

abstract class BasePresenter<MODEL : BaseModel<*>, VIEW : BaseView> {
  private var _view: VIEW? = null
  private var _model: MODEL = BaseModel<Any>() as MODEL
  
  val view
    get() = _view
  val model
    get() = _model

  open fun bind(model: MODEL, view: VIEW) {
    this._view = view
    this._model = model
  }

  open fun viewReady(first: Boolean = true) {}

  open fun unbind() {
    _view = null
  }
}

BaseStatelessActivity.kt

abstract class BaseStatelessActivity<VIEW : BaseView, out PRESENTER : BaseStatelessPresenter<VIEW>> : AppCompatActivity() {
  protected abstract val presenter: PRESENTER

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    presenter.bind(this as VIEW)
  }

  override fun onPostCreate(savedInstanceState: Bundle?) {
    super.onPostCreate(savedInstanceState)
    presenter.viewReady(first = savedInstanceState == null)
  }

  override fun onDestroy() {
    super.onDestroy()
    presenter.unbind()
  }
}

BaseStatelessPresenter.kt

abstract class BaseStatelessPresenter<VIEW : BaseView> {
  private var _view: VIEW? = null

  val view
    get() = _view

  open fun bind(view: VIEW) {
    this._view = view
  }

  open fun viewReady(first: Boolean = true) {}

  open fun unbind() {
    _view = null
  }
}

BaseView.kt

interface BaseView

MainActivityPresenter.kt

class MainActivityPresenter : BasePresenter<MainActivityModel, MainActivityPresenter.Contract>() {  
  interface Contract : BaseView {
  }
}

MainActivityView.kt

class MainActivityView : BaseActivity<MainActivityModel, MainActivityPresenter.Contract, MainActivityPresenter>(), MainActivityPresenter.Contract {
  override val presenter = MainActivityPresenter()

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
  }
}