Experimenting Architecture for Android

Recently I've been learning about architecture for Android, I find the journey of learning this topic pretty tough, so I hope to share my finding in this talk!

1. EXPERIMENTING WITH ARCHITECTURE FOR ANDROID 1
2. Tan JunRong Android Engineer 
3. 
4. Let’s Talk About Architecture ” “ 4
5. Why? Do We Really Need It? 5
6. Let’s Consider… Login Activity 6
10. NO ARCHITECTURE - Too coupled, hard to swap view/data source/ main logic - Activity becomes really long, hard to read - Hard to test, only with Espresso - etc 10
11. NO ARCH = MVC 11
12. CHOOSING ARCHITECTURE 12
13. WHICH!? MVVM DATABINDING MVP UNCLE BOB’S CLEAN ARCH MVVM RXJAVA 13
14. https://github.com/googlesamples/ android-architecture Official Google example on Github 14
16. MVVM DATABINDING MVP MVVM RXJAVA Today's Discussion MVP-VM 16
17. Need an example to compare… 17
19. No Architecture 19
20. No Arch nameEditText.addTextChangedListener(TextWatcherImp { s, _, _, _ ->
 name = s.toString()
 updateDisplayString()
 })
 
 favoriteAnimalEditText.addTextChangedListener(TextWatcherImp { s, _, _, _ ->
 animalName = s.toString()
 updateDisplayString()
 }) fun updateDisplayString() {
 displayTextView.text = name + " likes " + animalName
 } 20
21. Testing Strategy: No Arch 21
22. MVP 22
23. MVP: Activity nameET.addTextChangedListener({s ->
 mvpPresenter.onNameChange(s)
 })
 
 favoriteAnimalET.addTextChangedListener({ s ->
 mvpPresenter.onAnimalNameChange(s)
 }) override fun onDisplayStringUpdate(displayString: String) {
 displayTextView.text = displayString
 } Activity { } 23
24. MVP: Presenter override fun onNameChange(s: String) {
 name = s displayStringUpdate()
 }
 
 override fun onAnimalNameChange(s: String) {
 animalName = s displayStringUpdate()
 } fun displayStringUpdate() {
 view.onDisplayStringUpdate(name + " likes " + animalName)
 } Presenter { } 24
25. Testing Strategy: MVP 1 2 X 25
26. Testing Strategy: MVP practical 26
27. TEST - Test: states of the screen - Junit test: lightweight Code Wise - Decoupled - Readability / Consistency - Swap module (eg. view) easily MVP: advantage 27
28. MVVM 28
29. MVP MVVM 29 ObservableField
30. https://news.realm.io/news/eric-maxwell-mvc-mvp-and-mvvm-on-android/ This MVVM Example 30
31. MVP MVVM ViewModel has the same responsibility as Presenter 31
32. https://msdn.microsoft.com/en-us/library/hh848246.aspx Microsoft MVVM Diagram 32
33. The ViewModel and Presenter looks the same!? but wait, ViewModel has something different consider this… setting displayString ViewModel => displayString.set(“JR likes dog”) Presenter => view.updateDisplayString(“JR likes dog”) MVP vs MVVM 33
34. ViewModel => displayString.set(“JR likes dog”) Presenter => view.updateDisplayString(“JR likes dog”) Key Difference MVP MVVM BOUND! 34
35. OPERATIONS: same responsibility as Presenter in MVP View Model STATES: holding the state of views, bound with view + 35
36. Testing Strategy: MVVM Not too different from MVP, instead of testing View.methods(), we test on ViewModel’s state 36
37. RxJava 2 ways of doing MVVM Data Binding library from Google 37
38. Data Binding library from Google I use RxJava before trying this lib I find it hard to use logic inside XML, cannot be tested android:visibility = "@{viewModel.diplayString != null ? View.VISIBLE : View.GONE}" also, RxJava provides more, manipulating streams https://medium.com/@Miqubel/4-reasons-im-not-using-android-data-binding-e62127c2650c google this term: android data binding library bad idea ” “ Observable is not compatible with RxJava 38
39. RxJava Easier to use (if you’re already using RxJava) no spaghetti code inside xml you can do more, manipulating streams viewModel.displayStringObservable.subscribe { 
 displayTextView.text = it
 } https://github.com/worker8/learning-architecture-for-android 39
40. MVVM: advantage (SAME AS MVP) Key Difference - Deal with ViewModel, not View - (VM is bound to View automatically) TEST - Test: states of the screen - Junit test: lightweight Code Wise - Decoupled - Readability - Swap module (eg. view) easily 40
41. instead of checking view.action() My Opinion I like MVVM more I can test on view state directly from ViewModel disadvantage of mvvm: data binding library, remedied by RxJava 41
42. Test out yourself before choosing How to Choose? Remember the problem you’re trying to solve with arch Don’t focus on the solution! For trivial app, use no-architecture If project uses RxJava, use MVVM otherwise: use MVP personal advice… 42
43. MVVM DATABINDING MVP MVVM RXJAVA Today's Discussion MVP-VM 43
44. state + operations 44
45. state + operations what if we place operations back to Presenter? ViewModel only hold states now 45
46. MVVM MVP-VM 46
47. Since VM is separated, I’ll call it MVP-VM MVP-VM? 47
48. What difference does it make? persist MVP-VM VM 48
49. what does it mean? persist MVP-VM 49
50. Observable.combineLatest(input.name, input.favoriteAnimal, { name, favoriteAnimal -> MvpVmViewModel(name, favoriteAnimal, name + " likes " + favoriteAnimal)}) .subscribe(outputViewModel) I’m making new MvpVmViewModel in every mutation MvpVmViewModel MvpVmViewModel MvpVmViewModel MvpVmViewModel MVP-VM 50
51. Save state of screen to DB Example: Cookpad recipe editor page 51
52. Beyond that? 52
53. Since we have all the states of view… if we store them can we replay it? 
 yes, but not quite yet… Hmmm…. 53
54. REDUX Contract: Action No side effect: Pure reducer https://egghead.io/courses/getting-started-with-redux 54
55. Android Studio Plugin 55
57. https://github.com/worker8/learning-architecture-for-android/pull/1 Example done using Redux style 57
58. https://github.com/worker8/learning-architecture-for-android Github example https://github.com/kittinunf/remote-redux-devtools-android 58
59. Uncle Bob’s clean architecture What else is Out there? Redux : Front End Development VIPER: iOS https://medium.com/ios-os-x-development/ios-architecture-patterns-ecba4c38de52 59
60. tanjunrong@cookpad.com @worker8 Survey
 https://goo.gl/GU8vK2 60