Under Square's Hood

How Square uses Dagger, Flow and Mortar to build its Register app. Because Fragments hate you and want you to suffer.

1. Under Square’s Hood Ray Ryan
2. Square Style • Modularity viaViews • Injected by Dagger • Navigated by Flow • Presented and scoped by Mortar • Framework
3. Your Inalienable Right! to Modularity android.app.Activity android.app.Fragment android.view.View
4. Play
   
5. ! ! public7class7MainActivity7extends7Activity7{7 777 77@Override7protected7void7onCreate(Bundle7savedInstanceState)7{7 7777super.onCreate(savedInstanceState);7 !!!!setContentView(R.layout.root_layout);! 77}7 }7
6. ! ! ! <com.example.player.PlayerView! 7777xmlns:android="http://schemas.android.com/apk/res/android"7 7777android:orientation="vertical"7 7777android:layout_width="match_parent"7android:layout_height="match_parent">7 777777 !!!!<ImageView! 77777777android:layout_width="match_parent"7android:layout_height="0dp"7 77777777android:id="@+id/imageView"7 77777777android:layout_weight="1"/>7 !!!!<Button! 77777777android:layout_width="match_parent"7android:layout_height="wrap_content"7 77777777android:text="Play"7 77777777android:id="@+id/play_button"7 77777777android:layout_gravity="center_horizontal"7 77777777android:layout_weight="0"7 77777777android:layout_marginLeft="32dp"7android:layout_marginRight="32dp"7 77777777android:layout_marginTop="8dp"777android:layout_marginBottom="16dp"/>7 </com.example.player.PlayerView>7
7. ! ! public7class7PlayerView7extends7LinearLayout7{7 77private7final7Jukebox7jukebox;7 77private7final7Tweeter7tweeter;7 77 77public7PlayerView(Context7context,7AttributeSet7attrs)7{7 7777super(context,7attrs);7 7777PlayerApp7app7=7(PlayerApp)7context.getApplicationContext();7 7777jukebox7=7app.getJukebox();7 7777tweeter7=7app.getTweeter();7 77}7
8. ! ! 7@Override7protected7void7onFinishInflate()7{7 7777super.onFinishInflate();7 7777View7playButton7=7findViewById(R.id.play_button);! ! 7777playButton.setOnClickListener(new7OnClickListener()7{7 777777@Override7public7void7onClick(View7view)7{7 77777777if7(!jukebox.isPlaying())7{7 7777777777jukebox.play();7 7777777777tweeter.tweet("Playing7"7+7jukebox.playing().name());7 77777777}7else7{7 7777777777jukebox.stop();7 77777777}7 777777}7 7777});7 77}
9. ! ! public7class7PlayerApp7extends7Application7{7 77public7Jukebox7getJukebox()7{7 7777return7jukebox;7 77}7 77 77public7Tweeter7getTweeter()7{7 7777return7tweeter;7 77}! }7
10. Play
    PlayerApp Jukebox Tweeter
11. PlayerApp Tweeter TwitterApi Play
    Jukebox AudioStreamer
12. PlayerApp Play
    Tweeter Jukebox AudioStreamer TwitterApi OkHttpClient SharedPreferences
13. ! ! public7class7PlayerApp7extends7Application7{7 77 77private!AudioStreamer7audioStreamer;7 77private!OkHttpClient7httpClient;7 77private!Jukebox7jukebox;7 !!private!TwitterApi!twitterApi;! 77private!SharedPreferences7prefs;7 77private!Tweeter7tweeter;7 77
14. ! ! !7@Override7public7void7onCreate()7{7 7777super.onCreate();7 77 7777httpClient7=7new7OkHttpClient();7 7777audioStreamer7=7new7AudioStreamer(httpClient);7 7777twitterApi7=7new7TwitterApi(httpClient);7 77 7777prefs7=7getSharedPreferences("prefs",7MODE_PRIVATE);7 7777String7twitterUser7=7prefs.getString("twittercuser",7null);7 7777tweeter7=7new7Tweeter(twitterUser,7twitterApi);7 77 7777jukebox7=7new7Jukebox(audioStreamer);7 77}
15. That could turn into a lot of code
16. Dagger: @Inject Dependencies speakerdeck.com/jakewharton/android-apps-with-dagger-devoxx-2013
17. Dagger: @Inject Dependencies • Guicecc code generated, Android friendly, fast fast • @Inject “I want…” • @Module + @Provides “I make…”
18. Requesting Dependencies (“I want…”) • @Inject annotation required • Field injection • Constructor injection
19. Field Injection • @Inject on fields which are dependencies • For the stuff created by Android — Activity,View • Self inflicted
20. ! ! public7class7PlayerView7extends7LinearLayout7{7 77private7final7Jukebox7jukebox;7 77private7final7Tweeter7tweeter;7 77 77public7PlayerView(Context7context,7AttributeSet7attrs)7{7 7777super(context,7attrs);7 7777PlayerApp7app7=77 77777777(PlayerApp)7context.getApplicationContext();7 7777jukebox7=7app.getJukebox();7 7777tweeter7=7app.getTweeter();7 77}7 }7
21. ! ! public7class7PlayerView7extends7LinearLayout7{7 77@Inject7Jukebox7jukebox;7 77@Inject7Tweeter7tweeter;7 77 77public7PlayerView(Context7context,7AttributeSet7attrs)7{7 7777super(context,7attrs);7 7777PlayerApp7app7=77 77777777(PlayerApp)7context.getApplicationContext();7 7777app.inject(this);7 77}! }7
22. Constructor Injection • @Inject on a single constructor • Dagger creates the object
23. ! ! @Singleton7 public7class7Jukebox7{7 77private7final7AudioStreamer7streamer;7 77 77@Inject7 77public7Jukebox(AudioStreamer7streamer)7{7 7777this.streamer7=7streamer;7 7}7 }7
24. Providing Dependencies (“I make…”) • Constructor injected classes are good to go • Modules are classes that provide dependencies • @Module annotation on the module class • @Provides annotation on its factory methods • @Inject + @Module => ObjectGraph
25. AudioStreamer TwitterApi OkHttpClient
26. ! public7class7CloudModule7{7 77 77public7OkHttpClient7provideHttpClient()7{7 7777return7new7OkHttpClient();7 77}7 ! 777 77TwitterApi7provideTwitterApi(OkHttpClient7client)7{7 7777return7new7TwitterApi(client);7 77}7 777 77 77AudioStreamer7provideAudioStreamer(OkHttpClient7client)7{7 7777return7new7AudioStreamer(client);7 77}7 }
27. @Module7 public7class7CloudModule7{7 77 77public7OkHttpClient7provideHttpClient()7{7 7777return7new7OkHttpClient();7 77}7 77 777 77TwitterApi7provideTwitterApi(OkHttpClient7client)7{7 7777return7new7TwitterApi(client);7 77}7 777 77 77AudioStreamer7provideAudioStreamer(OkHttpClient7client)7{7 7777return7new7AudioStreamer(client);7 77}7 }7
28. @Module7 public7class7CloudModule7{7 77@Provides7 77public7OkHttpClient7provideHttpClient()7{7 7777return7new7OkHttpClient();7 77}7 77 77@Provides77 77TwitterApi7provideTwitterApi(OkHttpClient7client)7{7 7777return7new7TwitterApi(client);7 77}7 777 77@Provides7 77AudioStreamer7provideAudioStreamer(OkHttpClient7client)7{7 7777return7new7AudioStreamer(client);7 77}7 }7
29. @Module7 public7class7CloudModule7{7 77@Provides7@Singleton7 77public7OkHttpClient7provideHttpClient()7{7 7777return7new7OkHttpClient();7 77}7 77 77@Provides7@Singleton77 77TwitterApi7provideTwitterApi(OkHttpClient7client)7{7 7777return7new7TwitterApi(client);7 77}7 777 77@Provides7@Singleton7 77AudioStreamer7provideAudioStreamer(OkHttpClient7client)7{7 7777return7new7AudioStreamer(client);7 77}7 }7
30. ! public7class7PlayerApp7extends7Application7{7 77private7ObjectGraph7objectGraph;7 77 77@Override7public7void7onCreate()7{7 7777super.onCreate();7 77777 7777objectGraph7=7ObjectGraph.create(7 77777777new7CloudModule(),7 77777777new7AppModule(this)7 !!!!);! 77}7 77 77public7<T>7T7inject(T!thing)7{7 7777return7objectGraph.inject(thing);7 77}7 }
31. Square Style • Modularity via Views! • Injected by Dagger! • Navigated by Flow! • Presented and scoped by Mortar ✓ ✓
32. Play
    
33. Play
    Constantinople Sinister Exager… The Booker… Blue Rosebuds Laughing Song Bach is Dead Elvis & His Boss Laughing Song
34. Flow: minimalist backstack Courtesy of Logan Johnson
35. Flow: minimalist backstack • Stack of POJO “Screens,” like Intents or URLs
36. Constantinople Sinister Exager… The Booker… Blue Rosebuds Laughing Song Bach is Dead Elvis & His Boss Laughing Song Play
    AlbumListScreen7{7 } AlbumScreen7{7 77id7=723422;77 } TrackScreen7{77 77album7=723422;7 77track7=71;7 }
37. ! public7class7AlbumListView7extends7LinearLayout7{7 77@Inject7Jukebox7jukebox;7 77@Inject7Flow7flow;7 ! 77@Override7protected7void7onFinishInflate()7{7 7777super.onFinishInflate();7 77 7777listView7=7findById(this,7R.id.album_list);7 7777adapter7=7new7AlbumListAdapter(jukebox);7 7777listView.setAdapter(adapter);7 77 7777listView.setOnItemClickListener(new7OnItemClickListener()7{7 777777@Override7public7void7onItemClick(AdapterView<?>7parent,77 7777777777View7view,7int7position,7long7id)7{7 77777777flow.goTo(new7AlbumScreen(id));7 777777}7 7777});7 77}
38. ! ! @Layout(R.layout.album_view)7 public7class7AlbumScreen7{7 77public7final7int7id;7 77 77public7AlbumScreen(int7id)7{7 7777this.id7=7id;7 77}7 77 77@Override7 77public7boolean7equals(Object7o)7{7...7}7 77 77@Override7 77public7int7hashCode()7{7...7}! }7
39. Flow: minimalist backstack • Stack of POJO “Screens,” like Intents or URLs • Store the flow Backstack in the Activity Bundle • Show screens when you’re told to
40. ! public7class7MainActivity7extends7Activity77 7777implements7Flow.Listener7{7 ! 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);7 7777setContentView(R.layout.root_layout);7 ! !!!!Backstack7backstack;7 7777if7(b7==7null)7{7 777777backstack7=7Backstack.single(new7AlbumList());7 7777}7else7{7 777777backstack7=77 7777777777Backstack.from(b.getParcelable(BACKSTACK),7parcer);7 7777}7 77 7777flow7=7new7Flow(backstack,7this);7 7777go(flow.getBackstack(),7REPLACE,7null);7 77}7
41. ! public7class7MainActivity7extends7Activity77 7777implements7Flow.Listener7{7 ! 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);7 7777setContentView(R.layout.root_layout);7 ! !!!!Backstack7backstack;7 7777if7(b7==7null)7{7 777777backstack7=7Backstack.single(new7AlbumList());7 7777}7else7{7 777777backstack7=77 7777777777Backstack.from(b.getParcelable(BACKSTACK),7parcer);7 7777}7 77 7777flow7=7new7Flow(backstack,7this);7 7777go(flow.getBackstack(),7REPLACE,7null);7 77}7
42. ! ! 77/**#Flow.Listener#*/7 77@Override7public7void7go(Backstack7backstack,77 777777Flow.Direction7direction,7Flow.Callback7callback)7{7 7777Object7screen7=7backstack.current().getScreen();7 7777View7newView7=7Layouts.createView(this,7screen);7 77 7777setContentView(newView);7 7777callback.onComplete();7 77}
43. Flow: minimalist backstack • Stack of POJO “Screens,” like Intents or URLs • Store the flow Backstack in the Activity Bundle • Show screens when you’re told to • Flow#goBack(), Flow#goUp()
44. ! ! ##/**#Device#back#button#pressed#*/# 77@Override7public7void7onBackPressed()7{7 7777if7(!flow.goBack())7super.onBackPressed();7 77}7 ! 77@Override77 77public7boolean7onOptionItemSelected(MenuItem!item)7{7 7777//7Android7ActionBar7“Up/Home”7button7pressed.7 7777if7(item.getItemId()7==7android.R.id.home)7{7 777777return7flow.goUp();7 7777}7 77777 7777return7super.onOptionsItemSelected(item);7 77}7
45. ! ! @Layout(R.layout.track_view)7 public7class7TrackScreen7implements7HasParent7{7 77public7final7int7albumId;7 77public7final7int7trackId;7 77 77public7TrackScreen(int7albumId,7int7trackId)7{7 7777this.albumId7=7albumId;7 7777this.trackId7=7trackId;7 77}7 77 77@Override7public7AlbumScreen7getParent()7{7 7777return7new7AlbumScreen(albumId);7 77}7 !
46. Too Good to Be True? Yeah, probably
47. Flow: minimalist backstack AppFlow ScreenSwitcher
48. ! ! public7class7MainActivity7extends7Activity77 7777implements7Flow.Listener7{! ! !!private7final7FlowBundler7flowBundler7=77 7777new7FlowBundler(this)7{
 7777@Override7protected7Backstack7getColdStartBackstack()7{
 777777return7Backstack.single(new7Albumlist());
 7777}
 77};
49. 77 77 ##/**#E.g.#FrameScreenSwitcherLayout#*/# 77CanShowView7container;7 77 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);7 7777setContentView(R.layout.root_layout);7 7777container7=7(CanShowView)7findViewById(R.id.container);7 77 7777flowBundler.onCreate(b);7 7777AppFlow.loadInitialScreen(this);7 77}7
50. ! ! 77/**#Flow.Listener#*/7 77@Override7public7void7go(Backstack7backstack,77 777777Flow.Direction7direction,7Flow.Callback7callback)7{7 ! 7777Screen7screen7=7(Screen)7backstack.current().getScreen();! 7777container.showScreen(screen,7direction,7callback);! }
51. ! ! ##/**#Device#back#button#pressed#*/# 77@Override7public7void7onBackPressed()7{7 7777if7(!container.onBackPressed())7super.onBackPressed();7 77}7 !
53. Listen Now My Library Playlists Radio Shop
54. ! ! ! public7class7MainActivity7extends7Activity77 7777implements7Flow.Listener7{! ! 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);! !!!!setContentView(R.layout.root_layout);! res/layout/root_layout.xml res/layoutXsw600dpXland/root_layout.xml
55. ! <com.example.flow.view.TabletLandscapeRoot7 7777xmlns:android="http://schemas.android.com/apk/res/android"7 77 7777android:id="@id/container"7 7777android:orientation="horizontal"7 7777android:layout_width="match_parent"7 7777android:layout_height="match_parent"7 7777>7 77<com.example.flow.view.NavList7 777777android:id=“@+id/nav_list"7 777777android:layout_weight="20"7 777777android:layout_width="0dp"7 777777android:layout_height="match_parent"7 777777/>7 77<com.example.flow.screenswitcher.FrameScreenSwitcherView7 777777android:id="@+id/detail"7 777777android:layout_weight="80"7 777777android:layout_width="0dp"7 777777android:layout_height="match_parent"7 777777/>7 </com.example.flow.view.TabletLandscapeRoot>7
56. ! ! public7class7TabletMasterDetailRoot7extends7LinearLayout7 7777implements7HandlesBack,7HandlesUp,7CanShowScreen7{7 ! 77@Override7public7void7showScreen(Screen7screen,77 777777Flow.Direction7direction,7Flow.Callback7callback)7{7 ! 7777navList.updateSelection(screen);7 7777detailContainer.showScreen(screen,7direction,7callback);7 77}
57. ! ! ##/**#This#is#how#a#real#Square#app#handles#modals.#*/## 77@Override7public7void7showScreen(Screen7screen,77 7777777final7Flow.Callback7callback)7{7 7777if7(screen7instanceof7ModalScreen)7{7 777777contentFrame.interceptTouches(true);7 777777modalContainer.showScreen(screen,7new7Flow.Callback()7{7 77777777@Override7public7void7onComplete()7{7 7777777777modalContainer.setVisibility(VISIBLE);7 7777777777callback.onComplete();7 77777777}7 777777});7 777777return;7 7777}7else7if7(screen7instanceof7RequiresMerchant)7{7
58. Did you see the cheat? @Inject Flow flow;
59. PlayerApp Tweeter Jukebox AudioStreamer TwitterApi OkHttpClient SharedPreferences
60. PlayerApp objectGraph JukeBox etc. MainActivity Flow Tweeter @Inject
61. PlayerApp objectGraph JukeBox etc. MainActivity Flow @Huh? Tweeter @Inject
62. MainActivity activityGraph rootGraph JukeBox etc. Flow Tweeter @Inject @Inject
63. ObjectGraph#plus() • Creates child graph, extends the parent with additional modules! • Allows creating “scopes” of dependencies
64. ! ! public7class7MainActivity7extends7Activity7implements7Flow.Listener7{! 77private7FlowBundler7flowBundler7=7...;7 777 77@dagger.Module(7 7777addsTo7=7AppModule.class,7 7777injects7=7{7 777777AlbumView.class,7AlbumListView.class,7TrackView.class7 7777})7 77public7class7Module7{7 7777@Provides7Flow7provideFlow()7{7 777777return7flowBundler.getFlow();7 7777}7 77}7
65. 777 ! 77private7ObjectGraph7activityGraph;7 ! 77public7<T>7T7inject(T7thing)7{7 7777return7activityGraph.inject(thing);7 77}7 ! 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);7 7777PlayerApp7app7=7(PlayerApp)7getApplication();7 7777activityGraph7=7app.getObjectGraph().plus(new7Module());7 7777 7777Backstack7backstack;7 7777if7(b7==7null)7{7 777777backstack7=7Backstack.single(new7AlbumList());7 7777}7else7{7 777777backstack7=77 7777777777Backstack.from(b.getParcelable(BACKSTACK),7parcer);7
66. ! ! public7class7AlbumListView7extends7LinearLayout7{7 77@Inject7Jukebox7jukebox;7 77@Inject7Flow7flow;7 77 77public7AlbumListView(Context7context,7AttributeSet7attrs)7{7 7777super(context,7attrs);7 7777((MainActivity)context).inject(this);7 77}7 77 77@Override7protected7void7onFinishInflate()7{7 7777super.onFinishInflate();7 77 7777listView7=7findById(this,7R.id.album_list);7 7777final7adapter7=7new7AlbumListAdapter();7 7777listView.setAdapter(adapter);7 77 7777listView.setOnItemClickListener(new7OnItemClickListener()7{7
67. onConflagrationChange()
68. Play
    Play
    Play
    
69. Play
    Play
    
70. Play
    Play
    Presenter @Inject
71. Play
    Play
    Presenter @Inject
72. public7class7TrackView7extends7LinearLayout7{7 77@Inject7TrackViewPresenter7presenter;7 77 77@Override7protected7void7onFinishInflate()7{7 7777super.onFinishInflate();7 7777View7playButton7=7findViewById(R.id.play_button);7 7777playButton.setOnClickListener(new7OnClickListener()7{7 777777@Override7public7void7onClick(View7view)7{7 77777777presenter.onPlayClicked();7 777777}7 7777});7 7777presenter.takeView(this);7 77}7 77 77@Override7protected7void7onDetachedFromWindow()7{7 7777presenter.dropView(this);7 7777super.onDetachedFromWindow();7 77}7 }
73. ! ! @Singleton7 public7class7TrackViewPresenter7{7 77private7final7Jukebox7jukebox;7 77private7final7Flow7flow;7 77private7final7Tweeter7tweeter;7 77 77@Inject7 77public7TrackViewPresenter(Jukebox7jukebox,7Flow7flow,77 777777Tweeter7tweeter)7{7 7777this.jukebox7=7jukebox;7 7777this.flow7=7flow;7 7777this.tweeter7=7tweeter;7 77}7
74. ! ! 7public7void7onPlayClicked()7{7 7777if7(!jukebox.isPlaying())7{7 777777TrackScreen7screen7=7(TrackScreen)77 7777777777flow.getBackstack().current().getScreen();7 ! 777777jukebox.play(screen.albumId,7screen.trackId);7 777777tweeter.tweet("Playing7"7+7jukebox.playing().name());7 7777}7else7{7 777777jukebox.stop();7 7777}7 77}! }7
75. Square Style • Modularity via Views! • Injected by Dagger! • Navigated by Flow! • Presented and scoped by Mortar ✓ ✓ ✓
76. P
77. Constantinople Sinister Exager… The Booker… Blue Rosebuds Laughing Song Bach is Dead Elvis & His Boss Laughing Song P P
78. P Play
    P P
79. P Play
    
80. P Play
    
81. Mortar: managable, testable
82. Mortar: managable, testable • MortarScope enshrines, simplifies ObjectGraph.plus() • Scopes nest to arbitrary depths • Each screen can be a Blueprint for its own shortlived scope
83. ! ! @Layout(R.layout.track_view)7 public7class7TrackScreen7implements7HasParent7{7 77public7final7int7albumId;77 77public7final7int7trackId;7
84. ! ! @Layout(R.layout.track_view)7@WithModule(TrackScreen.Module.class)7 public7class7TrackScreen7implements7HasParent7{7 77public7final7int7albumId;7 77public7final7int7trackId;7 ! 77@dagger.Module(! !!!!addsTo7=7MainActivity.Module.class,7 7777injects7=7TrackView.class7 77)7 77class7Module7{7 7777@Provides7TrackScreen7provideScreen()7{77 777777return7TrackScreen.this;!! !!}7 }
85. @Singleton77 public7class7TrackViewPresenter7{7 77private7final7Jukebox7jukebox;7 77private7final7Flow7flow;7 77private7final7Tweeter7tweeter;7 77 77@Inject7public7TrackViewPresenter(Jukebox7jukebox,77 777777Flow7flow,7Tweeter7tweeter)7{7 7777this.jukebox7=7jukebox;7 7777this.flow7=7flow;7 7777this.tweeter7=7tweeter;7 77}7 ! 77public7void7onPlayClicked()7{7 777if7(!jukebox.isPlaying())7{7 777777TrackScreen7screen7=7(TrackScreen)77 7777777777flow.getBackstack().current().getScreen();7 ! 777777jukebox.play(screen.albumId,7screen.trackId);7
86. @Singleton7 public7class7TrackViewPresenter7{7 77private7final7Jukebox7jukebox;7 77private7final7TrackScreen7screen;7 77private7final7Tweeter7tweeter;7 77 77@Inject7public7TrackViewPresenter(Jukebox7jukebox,77 777777TrackScreen7screen,7Tweeter7tweeter)7{7 7777this.jukebox7=7jukebox;7 7777this.screen7=7screen;7 7777this.tweeter7=7tweeter;7 77}7 ! 77public7void7onPlayClicked()7{7 777if7(!jukebox.isPlaying())7{7 777777jukebox.play(screen.albumId,7screen.trackId);7 777777tweeter.tweet("Playing7"7+7jukebox.playing().name());7 7777}7else7{7 777777jukebox.stop();7
87. ! public7class7TrackViewPresenterTest7{! 77@Mock7Jukebox7jukebox;7 77@Mock7Tweeter7tweeter;7 77TrackScreen7screen7=7new7TrackScreen(100,75);77 ! 77TrackViewPresenter7presenter7=7 777777new7TrackViewPresenter(jukebox,7screen,7tweeter);7 77 77@Before7public7void7setup()7{7 7777initMocks(this);7 77}7 77 77@Test7public7void7playClick_stopsWhenPlaying()7{7 7777when(jukebox.isPlaying()).thenReturn(true);7 7777presenter.onPlayClicked();7 7777verify(jukebox).stop();7 77}7 }
88. Mortar: managable, testable • MortarScope enshrines, simplifies ObjectGraph.plus() • Scopes nest to arbitrary depths • Each screen can be a Blueprint for its own shortlived scope • Presenter class with onLoad(Bundle) and onSave(Bundle) lifecycle
89. ! ! @Singleton77 public7class7TrackViewPresenter7{7 77private7final7Jukebox7jukebox;7 77private7final7TrackScreen7screen;7 77private7final7Tweeter7tweeter;7 77 77@Inject7public7TrackViewPresenter(Jukebox7jukebox,77 777777Trackscreen7screen,7Tweeter7tweeter)7{7 7777this.jukebox7=7jukebox;7 7777this.screen7=7screen;7 7777this.tweeter7=7tweeter;7 77}7 ! 77public7void7onPlayClicked()7{7 777if7(!jukebox.isPlaying())7{7 777777jukebox.play(screen.albumId,7screen.trackId);7 777777tweeter.tweet("Playing7"7+7jukebox.playing().name());7
90. ! ! @Singleton77 public7class7TrackViewPresenter7extends7ViewPresenter<TrackView>7{7 77private7final7Jukebox7jukebox;7 77private7final7TrackScreen7screen;7 77private7final7Tweeter7tweeter;7 77 77@Inject7public7TrackViewPresenter(Jukebox7jukebox,77 777777Trackscreen7screen,7Tweeter7tweeter)7{7 7777this.jukebox7=7jukebox;7 7777this.screen7=7screen;7 7777this.tweeter7=7tweeter;7 77}7 ! 77public7void7onPlayClicked()7{7 777if7(!jukebox.isPlaying())7{7 777777jukebox.play(screen.albumId,7screen.trackId);7 777777tweeter.tweet("Playing7"7+7jukebox.playing().name());7
91. ! ! /**#Called#the#view#takes#this#presenter.#*/7 void7onEnterScope()7{! }7 ! /**#Called#each#time#takeView()#receives#a#new#view.#*/7 void7onLoad(Bundle7savedInstanceState)!{! !!getView().setStuffUpIGuess();! }7 ! /**#Called#from#Activity#onSaveInstanceState.#*/7 void7onSave(Bundle7outState)!{! }7 ! /**#Called#when#the#scope#is#destroyed.#*/7 void7onExitScope()7{! }7
92. Mortar: managable, testable • MortarScope enshrines, simplifies ObjectGraph.plus() • Scopes nest to arbitrary depths • Each screen can be a Blueprint for its own shortlived scope • Presenter class with onLoad(Bundle) and onSave(Bundle) lifecycle • Rooted in the Application and Activity
93. ! public7class7PlayerApp7extends7Application7{7 77private7ObjectGraph7objectGraph;7 77 77@Override7public7void7onCreate()7{7 7777super.onCreate();7 77 7777objectGraph7=7ObjectGraph.create(new7AppModule(this));7 77}7 77 77public7ObjectGraph7getObjectGraph()7{7 7777return7objectGraph;7 77}7 }
94. ! public7class7PlayerApp7extends7Application7{7 77private7MortarScope7rootScope;7 77 77@Override7public7void7onCreate()7{7 7777super.onCreate();7 77 7777rootScope7=7Mortar.createRootScope(new7AppModule(this));7 77}7 77 77@Override7public7Object7getSystemService(String7name)7{7 7777if7(Mortar.isScopeSystemService(name))7{7 777777return7rootScope;7 7777}7 77 7777return7super.getSystemService(name);7 77}7 }7
95. 777 public7class7MainActivity7extends7Activity7implements7Flow.Listener7{7 77private7ObjectGraph7activityGraph;7 ! 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);! !!!!setContentView(R.layout.root_layout);! ! 7777PlayerApp7app7=7(PlayerApp)7getApplication();7 7777activityGraph7=7app.getObjectGraph().plus(new7Module());7 7777 7777Backstack7backstack;7 7777if7(b7==7null)7{7 777777backstack7=7Backstack.single(new7AlbumList());7 7777}7else7{7 777777backstack7=77 7777777777Backstack.from(b.getParcelable(BACKSTACK),7parcer);7 7777}7 77
96. 777 public7class7MainActivity7extends7Activity7implements7Flow.Listener7{7 77private7ObjectGraph7activityGraph;7 ! 77@Override7protected7void7onCreate(Bundle7b)7{7 7777super.onCreate(b);! !!!!setContentView(R.layout.root_layout);! 77 7777MortarScope7parentScope7=7Mortar.getScope(getApplication());7 7777activityScope7=7Mortar7 77777777.requireActivityScope(parentScope,7new7Blueprint());7 77 7777Backstack7backstack;7 7777if7(b7==7null)7{7 777777backstack7=7Backstack.single(new7AlbumList());7 7777}7else7{7 777777backstack7=77 7777777777Backstack.from(b.getParcelable(BACKSTACK),7parcer);7 7777}7
97. 777 ! ! 77public7<T>7T7inject(T!thing)7{7 7777return7activityGraph.inject(thing);7 77}! ! ! ! 77 77public7AlbumListView(Context7context,7AttributeSet7attrs)7{7 7777super(context,7attrs);7 7777((MainActivity)context).inject(this);7 77}7
98. ! ! 77@Override7public7Object7getSystemService(String7name)7{7 7777if7(Mortar.isScopeSystemService(name))7{7 777777return7activityScope;7 7777}! !777return7super.getSystemService(name);7 77}7 ! ! 77public7AlbumListView(Context7context,7AttributeSet7attrs)7{7 7777super(context,7attrs);7 7777Mortar.inject(context,!this);7 77}7
99. Square Style • Modularity via Views! • Injected by Dagger! • Navigated by Flow! • Presented and scoped by Mortar ✓ ✓ ✓ ✓
100. Resources • square.github.io/dagger! • speakerdeck.com/jakewharton/android-apps-with-dagger-devoxx-2013! • github.com/square/flow! • github.com/square/mortar • square.com/careers
101. Resources • square.github.io/dagger! • speakerdeck.com/jakewharton/android-apps-with-dagger-devoxx-2013! • github.com/square/flow! • github.com/square/mortar • square.com/careers