Android development like a pro

Repo: https://github.com/rallat/EffectiveAndroid

Slides from the talk http://www.meetup.com/sfandroid/events/224952292/

The talk will show how to make your app scalable, your code clean, your performance optimized and your UI neat. The talk will show in a pragmatic way the pros and cons of using certain Android APIs, strategies and libraries.

Transcript

1. Android development like a pro #AndroidDevPro September 29, 2015
2. Israel Camacho September 29, 2015 Android Engineer at Twitter #AndroidDevPro
4. Fragment
5. Fragment AsyncTask
6. Fragment AsyncTask Loader
10. What is your goal?
11. Reliable, Scalable and Maintainable
13. Deliver
14. Deliver Really
15. Deliver Really Awesome
16. Deliver Really Awesome Features
17. Deliver Really Awesome Features Fast
19. Reliable, Scalable and Maintainable
20. Architecture Test
22. Fragments
23. Pros Encapsulates full features (multiples views, asynctasks, loaders). Reusable between different Activities.
24. Burrito design pattern
28. It doesn’t help to decouple your business logic!
32. WHY!?
33. WHY!?
34. Alternatives Single activity + navigation manager Many activities with reusable views
35. LaunchActivity NavigationManager Uri: “”
36. LaunchActivity NavigationManager startScreen(Screen1.class) Uri: “”
37. LaunchActivity NavigationManager startScreen(Screen1.class) inflates(Screen1.class) Uri: “screen1”
38. Screen1 URI: screen1 LaunchActivity NavigationManager startScreen(Screen1.class) inflates(Screen1.class) Uri: “screen1”
39. Screen1 URI: screen1 LaunchActivity NavigationManager startScreen(Screen1.class) inflates(Screen1.class) Uri: “screen1” User starts screen 2
40. Screen1 URI: screen1 LaunchActivity NavigationManager inflates(Screen1.class) startScreen(Screen2.class) Uri: “screen1” User starts screen 2
41. Screen1 URI: screen1 LaunchActivity Screen2 URI: screen2 NavigationManager startScreen(Screen2.class) Uri: “screen1/screen2” inflates(Screen2class) User starts screen 2
42. LET ME EXPLAIN YOU ANDROID LIKE A PRO
43. Let’s make an app
46. “Decouple your app from implementation details" - Anonymous
47. public interface ImageLoader { void load(ImageView view, String url); void loadWithTransformation(ImageView view, String url, Transformation transformation); }
48. public class PicassoImageLoader implements ImageLoader { private final Picasso picasso; … @Override public void load(ImageView view, String url) { picasso.load(url).into(view); } @Override public void loadWithTransformation(ImageView view, String url, Transformation transformation) { picasso.load(url).transform(transformation).into(view); } }
49. public class GlideImageLoader implements ImageLoader { private final Glide glide; … @Override public void load(ImageView view, String url) { glide.load(url).into(view); } @Override public void loadWithTransformation(ImageView view, String url, Transformation transformation) { glide.load(url).transform(transformation).into(view); } }
50. Common UI
52. Toolbar DrawerLayout
53. public interface ScreenContainer { /** * The root {@link android.view.ViewGroup} into which the activity should place its contents. */ ViewGroup bind(AppCompatActivity activity); /** * Returns the drawerLayout of this window. * */ DrawerLayout getDrawerLayout(); }
54. public abstract class EffectiveActivity extends AppCompatActivity { private ViewGroup mainFrame; private ScreenContainerImpl screenContainer; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); screenContainer = new ScreenContainerImpl(); mainFrame = screenContainer.bind(this); getLayoutInflater().inflate(getLayout(), mainFrame); ButterKnife.bind(this); } @NonNull abstract int getLayout(); }
55. public abstract class EffectiveActivity extends AppCompatActivity { private ViewGroup mainFrame; private ScreenContainerImpl screenContainer; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); screenContainer = new ScreenContainerImpl(); mainFrame = screenContainer.bind(this); getLayoutInflater().inflate(getLayout(), mainFrame); ButterKnife.bind(this); } @NonNull abstract int getLayout(); }
56. public abstract class EffectiveActivity extends AppCompatActivity { private ViewGroup mainFrame; private ScreenContainerImpl screenContainer; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); screenContainer = new ScreenContainerImpl(); mainFrame = screenContainer.bind(this); getLayoutInflater().inflate(getLayout(), mainFrame); ButterKnife.bind(this); } @NonNull abstract int getLayout(); }
57. public abstract class EffectiveActivity extends AppCompatActivity { private ViewGroup mainFrame; private ScreenContainerImpl screenContainer; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); screenContainer = new ScreenContainerImpl(); mainFrame = screenContainer.bind(this); getLayoutInflater().inflate(getLayout(), mainFrame); ButterKnife.bind(this); } @NonNull abstract int getLayout(); }
58. MVP Clean Architecture
59. View Presenter Model User Interaction
60. View Presenter Model User Interaction notify user event
61. View Presenter Model User Interaction notify user event request data
62. View Presenter Model User Interaction notify user event request data delivers entities
63. View Presenter Model User Interaction notify user event request data delivers entities update UI with entities
65. View
66. public interface TopImagesListView { void setImages(List<Image> images); void logout(); }
67. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { ... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setUpView(); presenter = new TopImagesListPresenterImpl(); presenter.create(); } @Override public void setImages(List<Image> images) { adapter = new ImageRecyclerView(images); recyclerView.setAdapter(adapter); } @Override public void logout() { TwitterCore.getInstance().logOut(); finish(); startActivity(new Intent(this, LoginActivity.class)); } ... }
68. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { ... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setUpView(); presenter = new TopImagesListPresenterImpl(); presenter.create(); } @Override public void setImages(List<Image> images) { adapter = new ImageRecyclerView(images); recyclerView.setAdapter(adapter); } @Override public void logout() { TwitterCore.getInstance().logOut(); finish(); startActivity(new Intent(this, LoginActivity.class)); } ... }
69. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { ... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setUpView(); presenter = new TopImagesListPresenterImpl(); presenter.create(); } @Override public void setImages(List<Image> images) { adapter = new ImageRecyclerView(images); recyclerView.setAdapter(adapter); } @Override public void logout() { TwitterCore.getInstance().logOut(); finish(); startActivity(new Intent(this, LoginActivity.class)); } ... }
70. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { ... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setUpView(); presenter = new TopImagesListPresenterImpl(); presenter.create(); } @Override public void setImages(List<Image> images) { adapter = new ImageRecyclerView(images); recyclerView.setAdapter(adapter); } @Override public void logout() { TwitterCore.getInstance().logOut(); finish(); startActivity(new Intent(this, LoginActivity.class)); } ... }
71. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { ... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setUpView(); presenter = new TopImagesListPresenterImpl(); presenter.create(); } @Override public void setImages(List<Image> images) { adapter = new ImageRecyclerView(images); recyclerView.setAdapter(adapter); } @Override public void logout() { TwitterCore.getInstance().logOut(); finish(); startActivity(new Intent(this, LoginActivity.class)); } ... }
72. Presenter
73. public interface TopImagesListPresenter extends Presenter { void create(); void setView(TopImagesListView view); }
74. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
75. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
76. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
77. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
78. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
79. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
80. public class TopImagesListPresenterImpl implements TopImagesListPresenter { private final ImageListModel model; private TopImagesListView view; private List<Image> viewArticles; … @Override public void create() { if (viewImages == null || viewImages.size() == 0) { viewImages = new ArrayList<>(); model.getMostRtImages(new WeakCallback(view, viewImages)); } else { if (view != null) { view.setImage(articles); } } } … }
81. public class TopImagesListPresenterImpl implements TopImagesListPresenter { … private static class WeakCallback extends Callback<List<Image>> { private WeakReference<TopImagesListView> view; private List<Image> imagesList; … @Override public void success(Result<List<Image>> result) { if (view.get() != null) { imagesList.addAll(result.data); view.get().setImage(result.data); } } @Override public void failure(TwitterException e) { if (view.get() != null) { view.get().logout(); } } } … }
82. public class TopImagesListPresenterImpl implements TopImagesListPresenter { … private static class WeakCallback extends Callback<List<Image>> { private WeakReference<TopImagesListView> view; private List<Image> imagesList; … @Override public void success(Result<List<Image>> result) { if (view.get() != null) { imagesList.addAll(result.data); view.get().setImage(result.data); } } @Override public void failure(TwitterException e) { if (view.get() != null) { view.get().logout(); } } } … }
83. public class TopImagesListPresenterImpl implements TopImagesListPresenter { … private static class WeakCallback extends Callback<List<Image>> { private WeakReference<TopImagesListView> view; private List<Image> imagesList; … @Override public void success(Result<List<Image>> result) { if (view.get() != null) { imagesList.addAll(result.data); view.get().setImage(result.data); } } @Override public void failure(TwitterException e) { if (view.get() != null) { view.get().logout(); } } } … }
84. Model
85. public interface TopImageListModel { void getMostRtImages(Callback<List<Image>> articles); }
86. public class TopImageListModelImpl implements TopImageListModel { private final CustomApiClient client; ... @Override public void getMostRtImages(final Callback<List<Image>> callback) { client.getTimelineService().homeTimeline(200, true, true, true, true, new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Image> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
87. public class TopImageListModelImpl implements TopImageListModel { private final CustomApiClient client; ... @Override public void getMostRtImages(final Callback<List<Image>> callback) { client.getTimelineService().homeTimeline(200, true, true, true, true, new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Image> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
88. public class TopImageListModelImpl implements TopImageListModel { private final CustomApiClient client; ... @Override public void getMostRtImages(final Callback<List<Image>> callback) { client.getTimelineService().homeTimeline(200, true, true, true, true, new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Image> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
89. public class TopImageListModelImpl implements TopImageListModel { private final CustomApiClient client; ... @Override public void getMostRtImages(final Callback<List<Image>> callback) { client.getTimelineService().homeTimeline(200, true, true, true, true, new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Image> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
90. public class TopImageListModelImpl implements TopImageListModel { private final CustomApiClient client; ... @Override public void getMostRtImages(final Callback<List<Image>> callback) { client.getTimelineService().homeTimeline(200, true, true, true, true, new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Image> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
91. Test
92. View: Test render logic and interaction with presenter, mock Presenter. Presenter: Test that view events invoke the right model method. mock both View and Model. Model: Test the business logic, mock the data source and Presenter.
93. MVP Pros Increases separation of concerns in 3 layers:
94. MVP Pros Increases separation of concerns in 3 layers: Presenter - Handle User events
95. MVP Pros Increases separation of concerns in 3 layers: Passive View - Render logic Presenter - Handle User events
96. MVP Pros Increases separation of concerns in 3 layers: Passive View - Render logic Presenter - Handle User events Model - Business logic
97. MVP Cons
98. MVP Cons BoilerPlate to wire the layers.
99. MVP Cons BoilerPlate to wire the layers. Model can’t be reused since is too tied to the specific use case.
100. MVP Cons BoilerPlate to wire the layers. Model can’t be reused since is too tied to the specific use case. View and Presenter are tied to data objects since they share the same type of object with the Model.
101. Orientation Change
102. PresenterHolder OnDestroy OnCreate Activity save presenter restore presenter onSavedInstanceState remove presenter if Activity is finishing then Running
103. public class EffectiveAndroidApplication extends Application { Map<Class, Presenter> presenterHolder; … public void putPresenter(Class c, Presenter p) { presenterHolder.put(c, p); } public <T extends Presenter> T getPresenter(Class<T> c) { return (T) presenterHolder.get(c); } public void remove(Class c) { presenterMap.remove(c); } }
104. public class PresenterHolder { static volatile PresenterHolder singleton = null; private Map<Class, Presenter> presenterMap; … public void putPresenter(Class c, Presenter p) { singleton.put(c, p); } public <T extends Presenter> T getPresenter(Class<T> c) { return (T) singleton.get(c); } public void remove(Class c) { presenterMap.remove(c); } }
105. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { … @Override protected void onCreate(Bundle savedInstanceState) { presenter = getPresenterHolder().getPresenter(TopImagesListActivity.class); presenter.create(); } @Override protected void onSaveInstanceState(Bundle bundle) { getPresenterHolder().putPresenter(TopImagesListActivity.class, presenter); } @Override protected void onDestroy() { super.onDestroy(); presenter.setView(null); if (isFinishing()) { getPresenterHolder().remove(TopImagesListActivity.class); } } }
106. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { … @Override protected void onCreate(Bundle savedInstanceState) { presenter = getPresenterHolder().getPresenter(TopImagesListActivity.class); presenter.create(); } @Override protected void onSaveInstanceState(Bundle bundle) { getPresenterHolder().putPresenter(TopImagesListActivity.class, presenter); } @Override protected void onDestroy() { super.onDestroy(); presenter.setView(null); if (isFinishing()) { getPresenterHolder().remove(TopImagesListActivity.class); } } }
107. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { … @Override protected void onCreate(Bundle savedInstanceState) { presenter = getPresenterHolder().getPresenter(TopImagesListActivity.class); presenter.create(); } @Override protected void onSaveInstanceState(Bundle bundle) { getPresenterHolder().putPresenter(TopImagesListActivity.class, presenter); } @Override protected void onDestroy() { super.onDestroy(); presenter.setView(null); if (isFinishing()) { getPresenterHolder().remove(TopImagesListActivity.class); } } }
108. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { … @Override protected void onCreate(Bundle savedInstanceState) { presenter = getPresenterHolder().getPresenter(TopImagesListActivity.class); presenter.create(); } @Override protected void onSaveInstanceState(Bundle bundle) { getPresenterHolder().putPresenter(TopImagesListActivity.class, presenter); } @Override protected void onDestroy() { super.onDestroy(); presenter.setView(null); if (isFinishing()) { getPresenterHolder().remove(TopImagesListActivity.class); } } }
109. public class TopImagesListActivity extends EffectiveActivity implements TopImagesListView { … @Override protected void onCreate(Bundle savedInstanceState) { presenter = getPresenterHolder().getPresenter(TopImagesListActivity.class); presenter.create(); } @Override protected void onSaveInstanceState(Bundle bundle) { getPresenterHolder().putPresenter(TopImagesListActivity.class, presenter); } @Override protected void onDestroy() { super.onDestroy(); presenter.setView(null); if (isFinishing()) { getPresenterHolder().remove(TopImagesListActivity.class); } } }
110. Clean Architecture MVP
111. “The clean architecture” - Uncle Bob
112. View Presenter Repository Presentation Layer Domain Layer Interactor Entity Entity Entity Interactor Interactor Data Layer ViewEntity User Interaction
113. Presentation Layer
114. View Presenter ViewEntity User Interaction
115. Use different entities from the interactor and domain layer.
116. Use different entities from the interactor and domain layer. Decouples from Use case modifications.
117. Use different entities from the interactor and domain layer. Decouples from Use case modifications. Represents data for the presentation layer.
118. Orientation Change
119. ViewEntityHolder OnDestroy OnCreate Activity save ViewEntity restore ViewEntity onSavedInstanceState remove ViewEntity if Activity is finishing then Running
120. Interactors
121. One use case per interactor maximize reusability
122. public interface GetTopArticles { void execute(Callback<List<Article>> articles); }
123. public class GetTopArticlesImpl implements GetTopArticles { private final TweetRepository tweetRepository; … @Override public void execute(final Callback<List<Article>> callback) { tweetRepository.getTimeline(new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Article> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
124. public class GetTopArticlesImpl implements GetTopArticles { private final TweetRepository tweetRepository; … @Override public void execute(final Callback<List<Article>> callback) { tweetRepository.getTimeline(new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Article> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
125. public class GetTopArticlesImpl implements GetTopArticles { private final TweetRepository tweetRepository; … @Override public void execute(final Callback<List<Article>> callback) { tweetRepository.getTimeline(new Callback<List<Tweet>>() { @Override public void success(Result<List<Tweet>> result) { final List<Article> items = processTweets(result); callback.success(items, null); } @Override public void failure(TwitterException e) { callback.failure(e); } }); } }
126. Repository
127. public interface TweetRepository { void getTimeline(final Callback<List<Tweet>> callback); void getTweet(String tweetId, final Callback<Tweet> callback); }
128. public class TweetRepositoryImpl implements TweetRepository { private final TwitterApiClient client; ... @Override public void getTimeline(final Callback<List<Tweet>> callback) { client.getTimelineService().homeTimeline(200, true, true, true, true, callback); } }
129. public class TweetRepositoryImpl implements TweetRepository { private final TwitterApiClient client; private final TweetCache cache; ... @Override public void getTimeline(final Callback<List<Tweet>> callback) { if (!cache.isEmpty()) { callback.success(cache.getTimeline()) } else { client.getTimelineService().homeTimeline(200, true, true, true, true,callback); } } }
130. public class TweetRepositoryImpl implements TweetRepository { private final TwitterApiClient client; private final TweetCache cache; private final TweetDB db; ... @Override public void getTimeline(final Callback<List<Tweet>> callback) { if (!cache.isEmpty()) { callback.success(cache.getTimeline()) } else if (!db.isEmpty()) { callback.success(db.getTimeline()) } else { client.getTimelineService().homeTimeline(200, true, true, true, true,callback); } } }
131. View Presenter Repository Presentation Layer Domain Layer Interactor Entity Entity Entity Interactor Interactor Data Layer ViewEntity User Interaction
132. Clean Architecture Benefits Presentation is decoupled from domain, that allows you to change the presentation pattern at anytime without changing any other layer.
133. Clean Architecture Benefits Domain layer allow new comers to understand use cases of the app. Interactor is just a function that gets an input and returns an output. It doesn’t care about representation or data sources. Domain layer can be a Java module!
134. Clean Architecture Benefits Data layer decouples the rest of the app from any change in the datasources and in the entities. Domain layer can be a Java module!
135. Let’s add infinite layers of separation!!!
137. Disadvantages Leads to Overengineering. Too much boilerplate code.
139. Thanks @fernando_cejas @wendi_ @loganj @joenrv @macarse
140. Questions? #AndroidDevPro We are hiring! israel@twitter.com Code: https://bit.ly/CleanAndroidRepo