Introduction to MV(Whatever) in Android

Introduce MVC, MVP (, and a little MVVM) patterns in Android and describe why we need these patterns to reduce the complexity of our applications.

Transcript

1. Introduction to MV(Whatever) in Android Elvis Lin 
 2016-11-24 @Android Taipei
2. Long time ago…
4. Huge Activities and Fragments • Hard to test • Impossible to unit test • Multiple responsibilities • Do complex animations • Modify and Retrieve data
5. Patterns
6. MV ( C | P | * )
7. MV ( C | P | * ) Model View
8. Model - View - Controller
9. View Controller Model User Input Update Model Query Data Update UI
10. Model - View - Controller in Android
11. View Controller Model User Input 1 … 1 Activity
12. Next Step: Remove Controller from Activity
13. View Controller Model User Input Update Model Query data Update UI Inform about input Notify view
14. Next Step: Model doesn’t refer to Activity/Fragment
15. View Controller Model 1 … 1 View Inferface
16. class Capital {
 String city;
 String nation;
 } displayCapital
 = city + “, ” + “nation”;
17. View? Capital capital
 = capitalModel.getCapital(); capitalTextView.setText(
 capital.getCity();
 + “, ”
 + capital.getNation();
18. Model? String capital = capitalModel
 .getDisplayCapital(); capitalTextView.setText(capital);
19. View/Model knows too much
20. View Controller Model 1 … 1 View Inferface
21. View Controller Model 1 … 1 View Inferface
22. Model - View - Presenter
23. View Presenter Model 1 … 1 IView IPresenter
24. View Presenter Update UI Inform User Action
25. View Presenter Model 1 … 1 IView IPresenter Contract
26. interface IView {
 void setCapital(String capital)
 }
27. ICapitalModle capitalModel;
 IView view; Presenter(ICapitalModel capitalModel,
 IView view) {
 this.capitalModel = capitalModel;
 this.view = view;
 }
28. interface IPresenter {
 void onLoad();
 }
29. @Override
 public void onLoad() {
 Capital capital 
 = capitalModel.getCapital;
 String displayCapital = 
 capital.getCity()
 + “, ”
 + capital.getNation();
 
 view.setCapital(displayCapital);
 }
30. @Override
 public void onLoad() {
 Capital capital 
 = capitalModel.getCapital;
 String displayCapital = 
 capital.getCity()
 + “, ”
 + capital.getNation();
 
 // Update UI
 view.setCapital(displayCapital);
 }
31. Easy to Unit Test
32. Unit Test of MVP
33. @Mock
 ICapitalModel capitalModel;
 
 @Mock
 IView view;
 
 Presenter presenter;
 
 @Before
 public void setup() {
 …
 presenter 
 = new Presenter(userModel, view)
 }
34. @Test
 public void displayCapital_onLoad() {
 when(capitalModel.getUser())
 .thenReturn(
 new Capital(“Tokyo”, “Japan”));
 
 presenter.onLoad();
 
 verify(view)
 .setCapital(“Tokyo, Japan”);
 }
35. Producer v.s. Consumer • When update UI • Presenter: Producer • View: Consumer
36. Android Architecture https://github.com/googlesamples/android- architecture
37. Sample:
 todo-mvp
38. List Add/Edit Detail
39. Todo Detail • TaskDetailActivity • TaskDetailContract • TaskDetailFragment • TaskDetailPresenter
40. Base Contract
41. View Presenter Communicate by contract
42. Presenter
43. View
44. Activity combines
 View and Presenter
45. ONE MORE THING…
46. Do we really need it? class IPresenter { void onLoad() {
 …
 view.setCapital(displayCapital);
 }
 
 }
47. MVVM
48. View ViewModel Model 1 … *
49. class ViewModel {
 
 Observable<String> getDisplayCapital() {
 ….
 }
 
 }
50. class View {
 …
 viewModel.getDisplayCapital().
 subscribe( capital ->
 setCapital(capital));
 …
 private void setCapital(String capital){
 capitalTextView.setText(capital);
 }
 }
51. • View register to ViewModel • ViewModel doesn’t update View • Tools: • RxJava • Data-binding
52. Conclusion • Separation of Concerns • Create common language in your team • Android framework logic free (do your best) • Can be tested by JUnit
53. Contact Info Elvis Lin • Github: 
 https://github.com/elvismetaphor • Blog: http://blog.elvismetaphor.me • Slides: https://speakerdeck.com/ elvismetaphor
54. Thank you!