Building complex Android apps these days might have some nasty challenges - syncing the data across the app, controlling any action the user does, processes that happen in the background or even handling all kinds of errors. Luckily enough Android developers are not the first to face these problems, so let's try to leverage existing solutions for our own good! In this talk, we'll share with you how Redux solved the problem of state management for Web developers and how can we use the same principles and integrate them into our Android apps.

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