Empower your app with MVP & Architecture Components

Empower your app with MVP & Architecture Components @ DevFestPisa 0.1

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1. Empower your app with MVP & Architecture Components Leonardo Pirro Android Developer @ IQUII @lpirro93
2. Who Am I? Hi, I’m Leo. Android Developer @ IQUII
3. What is MVP MVP stands for Model View Presenter and is a pattern responsible for the presentation layer.
4. Why use MVP?
5. Why use MVP? • Code maintainability • Code readability • Easy to add new features • Testing
6. Monte Prado 2054 m
7. Monte Prado 2054 m HomeActivity.java 2384 lines of code
8. Activity / Fragments Usually contain: • actions on Views • Handle clicks on UI elements • read/write in database / shared preferences / whatever • Network calls • Other stuff
9. Activity / Fragments Very hard to: • Read • Test • Refactor • Maintain • Reuse code
10. Separation Of Concerns && Single Responsibility
11. Model-View-Presenter
12. Model-View-Presenter
13. Model-View-Presenter
14. Model-View-Presenter View • Activity, Fragment, View • Propagates UI events to the presenter • Exposes methods that control presentation of data
15. Model-View-Presenter Presenter • Middle man between the View and Model • 100% pure Java (or Kotlin) code
16. Model-View-Presenter Model • Provides methods for data retrieval
18. Let’s go deeper
20. What we are gonna to build? A simple app with MVP pattern that loads Popular movies from the network
21. Moovie is here for you! I've created for you a simple app for better understanding what we're talking about! https://goo.gl/P1cS8J
22. The View
23. interface View { fun showLoadingView() fun hideLoadingView() fun showError(errorMessage: String) } View - The Base View
24. interface HomeContract{ interface ViewActions { fun getMovies() } interface HomeView: View { fun onMovieResult(movies: List<Movie>) } } The View Contract - HomeView
25. interface HomeContract{ interface ViewActions { fun getMovies() } interface HomeView: View { fun onMovieResult(movies: List<Movie>) } } The View Contract - HomeView interface ViewActions { fun getMovies() }
26. interface HomeContract{ interface ViewActions { fun getMovies() } interface HomeView: View { fun onMovieResult(movies: List<Movie>) } } The View Contract - HomeView interface HomeView: View { fun onMovieResult(movies: List<Movie>) }
27. interface HomeContract{ interface ViewActions { fun getMovies() } interface HomeView: View { fun onMovieResult(movies: List<Movie>) } } The View Contract - HomeView interface HomeView: View { fun onMovieResult(movies: List<Movie>) }
28. abstract class BasePresenter<V: Any>: Presenter { protected var mView: V? = null fun attachView(view: V) { mView = view } fun detachView() { mView = null } } Presenter - The Base Presenter
29. class HomePresenter (private val dataManager: DataManager) : BasePresenter<HomeView>(), HomeContract.ViewActions { private val mCompositeDisposable = CompositeDisposable() override fun unsubscribe() { mCompositeDisposable.clear() } override fun getMovies() { requestMovies() } private fun requestMovies(){ ... } } Presenter - The Home Presenter
30. class HomePresenter (private val dataManager: DataManager) : BasePresenter<HomeView>(), HomeContract.ViewActions { private val mCompositeDisposable = CompositeDisposable() override fun unsubscribe() { mCompositeDisposable.clear() } override fun getMovies() { requestMovies() } private fun requestMovies(){ ... } } Presenter - The Home Presenter ❌ Don’t let Presenters know about Android framework classes
31. class HomePresenter (private val dataManager: DataManager) : BasePresenter<HomeView>(), HomeContract.ViewActions { private val mCompositeDisposable = CompositeDisposable() override fun unsubscribe() { mCompositeDisposable.clear() } override fun getMovies() { requestMovies() } private fun requestMovies(){ ... } } Presenter - The Home Presenter class HomePresenter (private val dataManager: DataManager) : BasePresenter<HomeView>(), HomeContract.ViewActions { override fun getMovies() { requestMovies() } private fun requestMovies(){ ... }
32. Presenter - The Home Presenter private fun requestMovies(){ mView?.showLoadingView() val disposable = dataManager.getMovies() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .map { response -> response.results } .doFinally { mView?.hideLoadingView() } .subscribe( { movies -> mView?.onMovieResult(movies)}, { error: Throwable -> mView?.showError(error.localizedMessage)} ) mCompositeDisposable.add(disposable) } HomePresenter.kt
33. Presenter - Handling Result, Errors, Loading private fun requestMovies(){ mView?.showLoadingView() val disposable = dataManager.getMovies() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .map { response -> response.results } .doFinally { mView?.hideLoadingView() } .subscribe( { movies -> mView?.onMovieResult(movies)}, { error: Throwable -> mView?.showError(error.localizedMessage)} ) mCompositeDisposable.add(disposable) } .doFinally { mView?.hideLoadingView() } { movies -> mView?.onMovieResult(movies)}, { error: Throwable -> mView?.showError(error.localizedMessage)} mView?.showLoadingView() HomePresenter.kt
34. Activity class HomeActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) ... }t
35. Activity class HomeActivity : AppCompatActivity(), HomeContract.HomeView { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) ... }t
36. Activity class HomeActivity : AppCompatActivity(), HomeContract.HomeView { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) ... } override fun onMovieResult(movies: List<Movie>) {} override fun showLoadingView() {} override fun hideLoadingView() {} override fun showError(errorMessage: String) {}
37. Activity lateinit var presenter: HomePresenter override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) }t
38. Activity lateinit var presenter: HomePresenter override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) presenter = HomePresenter(DataManager) }t override fun onResume() { super.onResume() presenter.attachView(this) }
39. Activity lateinit var presenter: HomePresenter override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) presenter = HomePresenter(DataManager) } override fun onResume() { super.onResume() presenter.attachView(this) presenter.getMovies() }
40. Activity lateinit var presenter: HomePresenter override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) presenter = HomePresenter(DataManager) } override fun onStop() { super.onStop() presenter.detachView() presenter.unsubscribe() }
41. Model - DataManager object DataManager { private var sApiService: ApiService = ApiServiceFactory.makeApiService() /** * Get movies from the network */ fun getMovies(): Single<MoviesResponse> { return sApiService.getMovies() } }
42. Architecture Components
43. Architecture Components Room ViewModel LiveData
44. Architecture Components Room ViewModel LiveData
45. Room • Easily convert SQLite table data to Java objects • Avoid boilerplate code • Compile time checks of SQLite statements and can return RxJava, Flowable and LiveData observables
46. Room @Entity public class Student { @PrimaryKey private final int id; public final String name; public final String email; public Student(int id, String name, String email) { this.id = id; this.name = name; this.email = email; } }
47. Room We need to create the Data Access Object (aka DAO) @Dao public interface StudentDato { @Query("SELECT * FROM student") List<Student> getAllStudents(); @Insert void insert(Student... students); @Update void update(Student... students); @Delete void delete(Student... students); }
48. Room @Query("SELECT * FROM student") List<Student> getAllStudents(); @Query("SELECT * FROM student WHERE id=:id") Student getStudent(int id); @Query("SELECT * FROM student") Cursor getRepoCursor();
49. Room - The DataBase @Database(entities = { Student.class }, version = 1) public abstract class StudentDatabase extends RoomDatabase { private static final String DB_NAME = "studentDatabase.db"; private static volatile StudentDatabase instance; static synchronized StudentDatabase getInstance(Context context) { if (instance == null) { instance = create(context); } return instance; } private static StudentDatabase create(final Context context) { return Room.databaseBuilder( context, StudentDatabase.class, DB_NAME).build(); } public abstract StudentDao getStudentDao(); }
50. Architecture Components Room ViewModel LiveData
51. Architecture Components Room ViewModel LiveData
52. ViewModel • The ViewModel class is designed to store and manage UI- related data • Life-Cycle aware ( survive configuration changes such as screen rotations)
53. ViewModel
54. Architecture Components Room ViewModel LiveData
55. Architecture Components Room ViewModel LiveData
56. LiveData • Data holder class • Observable pattern • Life-Cycle aware ( AGAIN -survive configuration changes such as screen rotations)
57. ViewModel ❤ LiveData
58. ViewModel + LiveData public class MyViewModel extends ViewModel { private MutableLiveData<List<Student>> students; public LiveData<List<Student>> getStudents() { if (students == null) { students = new MutableLiveData<List<Student>>(); loadStudents(); } return students; } private void loadStudents() { // Do an asyncronous operation to fetch users. } }
59. ViewModel + LiveData public class MyActivity extends AppCompatActivity { public void onCreate(Bundle savedInstanceState) { MyViewModel model = ViewModelProviders.of(this).get(MyViewModel.class); model.getStudents().observe(this, students -> { // update UI }); } }
60. presentation.finish()
61. http://www.androiddevs.it Slack community - Android Developers Italia
62. Thank You Leonardo Pirro Android Developer @ IQUII @lpirro93