Clean, Easy & New Android Arch. : Devoxx-BE 17

Transcript

1. Clean, Easy & New Android Architecture Britt Barak Devoxx Belgium 2017
2. Britt Barak @brittBarak Android Developer & TL Android Academy Women Techmakers
3. And you...?
4. One thing is sure Everything will change. Quick.
5. My First Startup
6. “As You Like It” / W. Shakespeare ״All the world’s a stage, And all the men and women merely players; They have their exits and their entrances, And one man in his time plays many parts:״
7. Players Exits and Entrances Plays a part → Single responsibility → Defined interfaces → Separation of concerns
8. Our Goals - Write quicker - Change easily - Rely on the code (test) - Easy for others to understand
9. App Architecture with the new components
10. Who loves Jelly Beans?
15. Where to start?
16. Presentation Layer Data Layer Domain Layer
18. Is about: UI Is not about: logic. Presentation Layer
19. class JellyBeanViewModel extends ViewModel { String flavor; int r; int g; int b;
20. @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_add_bean); setViewModel() setUi(); }
21. void setViewModel(){ this.viewModel = new JellyBeanViewModel(); }
22. UI represents the ViewModel state
23. Presentation Layer Domain Layer View ViewModel User Input
24. 1. Update the viewModel
25. public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { switch (seekBar.getId()) { case R.id.sb_r: viewModel.setR(progress); break; //...
26. 2. View Model notifies
27. - Callbacks - Data binding - RxJava - LiveData How to notify?
28. LiveData - Observable data holder class - Lifecycle-aware - Updates only on started / resumed state - Removes itself on destroyed state - No memory leaks https://developer.android.com/topic/libraries/architecture/livedata.html
29. public class JellyBeanViewModel extends ViewModel { String flavor; LiveData<Integer> r; LiveData<Integer> g; LiveData<Integer> b;
30. public class JellyBeanViewModel extends ViewModel { LiveData<Integer> r; public void setR(int r) { r = validate(r); this.r.setValue(r); }
31. 3. Create an observer
32. Observer<Integer> colorChangedObserver = (Integer integer) -> { beanIv.setColorFilter(viewModel.getColor()); };
33. 4. Observe ViewModel changes
34. viewModel.getR() .observe(this, colorChangedObserver); Observer is tied to this lifecycle, and will be removed as the lifecycle ends. LivaData
35. Presentation Layer Domain Layer ViewModel View set() User Input notify
36. Persisting ViewModel
38. setViewModel() -> { this.viewModel = ViewModelProviders.of(this) .get(JellyBeanViewModel.class); }
39. And for more complex ViewModels?
40. 1. Multiple LiveData Objects 2. Separate class → Lifecycle Aware Suggestions: Peach Dream Peach Pie P
41. Save The Jelly Bean!
42. Is about: “objective” data Is not about: caring about the consumer Data Layer
43. - Data Model - Repository Data Layer
44. class JellyBeanViewModel String flavor; int r; int g; int b; class JellyBean String flavor; String color;
45. - One per data type (e.g jelly bean, recipe, user….). - Encapsulates the logic of getting/setting the data. - CRUD operations (Create, Read, Update, Delete) Repository
46. class JellyBeanRepo{ }
47. class JellyBeanRepo{ LiveData<JellyBean> getJellyBean(String id){ }
48. LiveData<JellyBean> getJellyBean(String id) { return myFirebaseClient.getJellyBean(id) }
49. LiveData<JellyBean> getJellyBean(String id) { if (cache.hasJellyBean(id)){ return cache.getJellyBean(id); } else{ return myFirebaseClient.getJellyBean(id) } }
50. LiveData<JellyBean> getJellyBean(String id) { if (cache.hasJellyBean(id)){ return cache.getJellyBean(id); } else if (appDatabase.hasJellyBean(id)) { return appDatabase.jellyBeanDao().getJellyBean(id); } else{ return myFirebaseClient.getJellyBean(id) }
51. LiveData<JellyBean> getJellyBean(String id) { if (cache.hasJellyBean(id)){ return cache.getJellyBean(id); } else if (appDatabase.hasJellyBean(id)) { return appDatabase.jellyBeanDao().getJellyBean(id); } else{ return myApiClient.getJellyBean(id) }
52. Presentation Layer Data Layer ViewModel DataModel ?
53. Presentation Layer Data Layer Domain Layer DataModel Interactor ViewModel
54. Is about: converting models Is not about: UI, Data Domain Layer
55. Save The Jelly Bean!
56. 1. Create Use Case
57. class SaveJellyBean extends UseCase { void execute() { }
58. 2. Convert Models
59. public class SaveJellyBean extends UseCase { public void execute(JellyBeanViewModel viewModel) { JellyBean data = prepareDataModel(viewModel); }
60. JellyBean prepareDataModel(JellyBeanViewModel viewModel){ String beanColorString = String.format("#%06X", (0xFFFFFF & viewModel.getColor())); JellyBean data = new JellyBean(viewModel.getFlavor(), beanColorString); return data; }
61. 3. Call Repository
62. public class SaveJellyBean extends UseCase { public void execute(JellyBeanViewModel viewModel) { JellyBean data = prepareDataModel(viewModel); repo.saveBean(data); }
63. 4. Execute
64. Presentation Layer Data Layer Domain Layer DataModel Interactor ViewModel
65. Presentation Layer Data Layer Domain Layer SaveJellyBean .execute() JellyBeanRepo .save()
66. Reusing interactors - Edit Jelly Bean screen - Different UI - Same SaveJellyBean use case
67. Some more about Repository...
68. Data Layer Network Service Local DB Cache? Domain Layer Some Usecase
69. Local database - Persistence between sessions - Single source of truth
70. Room - Wraps SQLite database - Generates boilerplate code - Verifies queries at compile time - Denies calls on the UI thread
71. 1. Create Entity
72. @Entity public class JellyBean { @PrimaryKey @NonNull String id; String flavor; String color;
73. 2. Create Dao
74. @Dao public interface JellyBeanDao { @Query("select * from jellyBean") LiveData<List<JellyBean>> getAllJellyBeans(); @Query("select * from jellyBean where id = :beanId") LiveData<JellyBean> getJellyBean(String beanId); }
75. @Insert(onConflict = REPLACE) void insertJellyBean(JellyBean jellyBean); @Delete void deleteJellyBean(JellyBean jellyBean);
76. 3. Create App Database instance
77. @Database(version = 1, entities = {JellyBean.class}) public abstract class AppDatabase extends RoomDatabase { private static AppDatabase instance; public abstract JellyBeanDao jellyBeanDao(); //init and destroy code.. }
78. public static AppDatabase getInMemoryDatabase(Context appContext){ if (instance == null) { instance = Room.inMemoryDatabaseBuilder( appContext, AppDatabase.class).build(); } return instance; } public static void destroyInstance() { instance = null; }
79. 4. Use from Repository
80. public LiveData<JellyBean> getJellyBean(String id) { if (cache.hasJellyBean(id)){ //… return appDatabase.jellyBeanDao().getJellyBean(id); //... }
81. Presentation Layer Data Layer Domain Layer SaveJellyBean .execute() JellyBeanRepo .save() LocalDB JellyBeanDao
82. Presentation Layer • View • ViewModel • Presenter Data Layer • Repository • DataModel Domain Layer • Interactor • Use case
83. Players Exits and Entrances Plays a part → Single responsibility → Defined interfaces → Separation of concerns
84. Our Goals - Write quicker - Change easily - Rely on the code (test) - Easy for others to understand
85. Get my notes on - @britt.barak Keep in touch! Britt Barak @brittBarak Thank you!
86. Thank You !