As presented in droidcon Tel Aviv 2018: http://il.droidcon.com

1. The Redux State
of the Art
Limor Mekaiten & Shem Magnezi

2. Managing
app state
We were all there

3. We
were
there
too

4. Facebook
we have a
problem

5. Introducing Flux

6. Then came Redux

7. Redux data flow

8. Store

9. Components / Views

10. Actions

11. Reducer

12. Let’s dive in
(in Kotlin)

13. data class AppState(val unreadConut: Int,
val notifications: List<Notification>)
Store

14. Store.init(AppState.new(0, emptyList()))
Store

15. //Notifications Activity
fun onCreate() {
Store.subscribe(this)
}
fun onStateChange(newState: AppState) {
notificationRecycleView.setNotifications(
newState.notifications)
}
View

16. data class MarkAllAsReadAction()
data class AddNotificationAction(notification:
Notification)
Actions

17. //Notifications Activity
markAllAsReadButton.onClick(click => {
Store.dispatch(MarkAsReadAction.new())
})
Actions

18. fun reduce(oldState: AppState, action: Action) : AppState {
return when (action) {
is MarkAllAsRead -> {
return oldState.copy(unreadConut = 0)
}
else -> oldState
}
}
Reducers

19. //Notifications ServiceWorker
fun onMessageReceived(remoteMessage: RemoteMessage) {
val notificationFromServer = Notificaiton.new(remoteMessage.msg)
Store.dispatch(AddNotificationAction.new(notificationFromServer))
}
Actions

20. fun reduce(oldState: AppState, action: Action) : AppState {
return when (action) {
is AddNotificationAction -> {
return oldState.copy(
unreadConut = oldState.unreadConut + 1,
notifications = action.notification +
oldState.notifications)
}
...
else -> oldState
}
}
Reducers

21. Redux data flow (again)

22. Redux - Why is it good for me?

23. Logic is made easy
● Implicit data flow of your app becomes explicit
● Easy to spot edge cases - you get to see the missing
cases now

24. Debugging is made easy
● Single source of truth
● Testing made easy -
issue the action, see
how your state changes
● Time travel

25. Summary

26. Building apps with a complex state can
be hard to develop and hard to debug

27. Redux can help you manage the app’s
state (and save you a lot of headaches)

28. Android can (and should) learn from
other platforms

29. More resources
Slides: http://shem8.github.io/talks/
Redux Docs: https://redux.js.org/
Dan Abramov’s talk: https://youtu.be/xsSnOQynTHs
Reductor: Redux implementation in Java: https://github.com/Yarikx/reductor
Bansa: Redux implementation in Kotlin: https://github.com/brianegan/bansa
Dan Abramov’s Redux tutorial:
https://egghead.io/courses/getting-started-with-redux

30. Join us!

31. limor.mekaiten
@gmail.com
smagnezi8
@gmail.com