Introduction to Dagger 2

An introduction covered with example codes to demonstrate the need and how to use in the simplest way possible the dependency injection framework "Dagger".

Transcript

1. Introduction to Dagger 2 Marcello Galhardo
2. @marcellogalhardo @marcellogalhardo @MarcelloGalhard marcello.galhardo@gmail.com /marcellogalhardo Android Dev BR slack.androiddevbr.org
3. Do you know... ...inversion of control?
4. Do you know... ...inversion of control? ...Dagger?
5. Why should I use Dependency Injection?
6. Easy reuse of components
7. Safer and easier refactoring
8. Easier testing
9. Activity
10. Presenter Activity
11. Presenter Repository Activity
12. Presenter Repository Activity Api
13. Presenter Repository Activity Cache Api
14. public class Activity extends AppCompatActivity { private Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); presenter = new Presenter(); } } public class Presenter { private Repository repository; public Presenter() { repository = new Repository(); } } Activity.java / Presenter.java
15. public class Activity extends AppCompatActivity { private Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); presenter = new Presenter(); } } public class Presenter { private Repository repository; public Presenter() { repository = new Repository(); } } Activity.java / Presenter.java
16. public class Activity extends AppCompatActivity { private Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); Api api = new Api(); Cache cache = new Cache(); Repository repository = new Repository(api, cache); presenter = new Presenter(repository); } } Activity.java
17. public class Activity extends AppCompatActivity { private Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); Api api = new Api(); Cache cache = new Cache(); Repository repository = new Repository(api, cache); presenter = new Presenter(repository); } } Activity.java
18. • Too much boilerplate code; Problems!
19. • Too much boilerplate code; • Hard to maintain the dependency graph. Problems!
20. Let's talk about Dagger
21. Dagger 2 • No Reflection;
22. Dagger 2 • No Reflection; • Code generated at build time;
23. Dagger 2 • No Reflection; • Code generated at build time; • Easy to debug;
24. Dagger 2 • No Reflection; • Code generated at build time; • Easy to debug; • Easy to maintain the dependency graph.
25. app/build.gradle dependencies { annotationProcessor "com.google.dagger:dagger-compiler:2.8" compile "com.google.dagger:dagger:2.8" provided "org.glassfish:javax.annotation:2.8" }
26. @Singleton @Component(modules = { MainModule.class, ...}) public interface MainComponent { void inject(Activity activity); } MainComponent.java
27. @Singleton @Component(modules = { MainModule.class, ...}) public interface MainComponent { void inject(Activity activity); } MainComponent.java
28. @Singleton @Component(modules = { MainModule.class, ...}) public interface MainComponent { void inject(Activity activity); } MainComponent.java
29. @Singleton @Component(modules = { MainModule.class, ...}) public interface MainComponent { void inject(Activity activity); } MainComponent.java
30. @Singleton @Component(modules = { MainModule.class, ...}) public interface MainComponent { void inject(Activity activity); } MainComponent.java
31. @Singleton @Component(modules = { MainModule.class, ...}) public interface MainComponent { void inject(Activity activity); } MainComponent.java
32. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
33. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
34. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
35. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
36. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
37. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
38. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
39. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
40. MainModule.java @Module public class MainModule { private static final int CACHE_SIZE_10_MB = 10 * 1024 * 1024; private static final int TIMEOUT = 20; @Provides public Presenter providesPresenter(Repository repository) { return new Presenter(repository); } @Provides @Reusable public Repository repository(Cache cache, Api api) { return new Repository(cache, api); } @Provides @Singleton public Cache providesCache() { return new Cache(CACHE_SIZE_10_MB); } @Provides @Reusable public Api providesApi() { return new Api(TIMEOUT); } }
41. MainApplication.java public class MainApplication extends Application { private MainComponent component; @Override public void onCreate() { super.onCreate(); component = DaggerMainComponent.builder().build(); } public MainComponent getComponent() { return component; } }
42. MainApplication.java public class MainApplication extends Application { private MainComponent component; @Override public void onCreate() { super.onCreate(); component = DaggerMainComponent.builder().build(); } public MainComponent getComponent() { return component; } }
43. MainApplication.java public class MainApplication extends Application { private MainComponent component; @Override public void onCreate() { super.onCreate(); component = DaggerMainComponent.builder().build(); } public MainComponent getComponent() { return component; } }
44. MainApplication.java public class MainApplication extends Application { private MainComponent component; @Override public void onCreate() { super.onCreate(); component = DaggerMainComponent.builder().build(); } public MainComponent getComponent() { return component; } }
45. Activity
46. Application Activity
47. Application Component Activity
48. Application Component Activity MainModule
49. Application Component Activity Modules... MainModule
50. Activity.java public class Activity extends AppCompatActivity { @Inject Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); MainApplication application = getMainApplication(); MainComponent component = application.getComponent(); component.inject(this); } }
51. Activity.java public class Activity extends AppCompatActivity { @Inject Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); MainApplication application = getMainApplication(); MainComponent component = application.getComponent(); component.inject(this); } }
52. Activity.java public class Activity extends AppCompatActivity { @Inject Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); MainApplication application = getMainApplication(); MainComponent component = application.getComponent(); component.inject(this); } }
53. Activity.java public class Activity extends AppCompatActivity { @Inject Presenter presenter; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); MainApplication application = getMainApplication(); MainComponent component = application.getComponent(); component.inject(this); } }
54. Repository Cache Api
55. Repository MockCache MockApi Api Cache
56. Examples
57. github.com/marcellogalhardo/events
58. github.com/marcellogalhardo/locations
59. Questions?
60. www.concretesolutions.com.br Rio de Janeiro – Rua São José, 90 – cj. 2121 Centro – (21) 2240-2030 São Paulo - Av. Nações Unidas, 11.541 3º andar - Brooklin - (11) 4119-0449 We help companies create successful digital products