Solving Android Inactive Lifecycle State Data Events in a Reactive Environment using Relays

LifecycleFriendlyReactiveSample.kt

package com.methodsignature.sample

import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import com.jakewharton.rxrelay2.BehaviorRelay
import io.reactivex.Observable
import io.reactivex.disposables.CompositeDisposable

data class Data(
    val id: Long,
    val text: String
)

class ViewDataInteractor {
    fun connect(): Observable<Data> {
        return Observable.just(Data(0, "text"))
    }
}

class Presenter(private val dataObservable: Observable<Data>) {

    private val disposables = CompositeDisposable()

    fun onStart() {
        val disposable = dataObservable.subscribe {
            // update UI
        }
        disposables.add(disposable)
    }

    fun onStop() {
        disposables.clear()
    }
}

class Activity: AppCompatActivity() {

    private lateinit var presenter: Presenter
    private val interactor = ViewDataInteractor()

    private val dataRelay = BehaviorRelay.create<Data>()
    private val disposables = CompositeDisposable()


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val disposable = interactor.connect()
            .subscribe {
                dataRelay.accept(it)
            }
        disposables.add(disposable)

        presenter = Presenter(dataRelay)
    }

    override fun onDestroy() {
        super.onDestroy()
        disposables.clear()
    }

    override fun onStart() {
        super.onStart()
        presenter.onStart()
    }

    override fun onStop() {
        super.onStop()
        presenter.onStop()
    }
}