Introduction to Dagger 2 Marcello Galhardo
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Introduction to Dagger 2Marcello Galhardo
@marcellogalhardo
@marcellogalhardo
@MarcelloGalhard
/marcellogalhardo
Android Dev BRslack.androiddevbr.org
Do you know...
...inversion of control?
Do you know...
...inversion of control?
...Dagger?
Why should I use Dependency Injection?
Easy reuse of components
Safer and easier
refactoring
Easier testing
Activity
Presenter
Activity
Presenter
Repository
Activity
Presenter
Repository
Activity
Api
Presenter
Repository
Activity
CacheApi
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
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
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
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
● Too much boilerplate code;
Problems!
● Too much boilerplate code;
● Hard to maintain the dependency graph.
Problems!
Let's talk about Dagger
Dagger 2
● No Reflection;
Dagger 2
● No Reflection;
● Code generated at build time;
Dagger 2
● No Reflection;
● Code generated at build time;
● Easy to debug;
Dagger 2
● No Reflection;
● Code generated at build time;
● Easy to debug;
● Easy to maintain the dependency graph.
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"}
@Singleton@Component(modules = { MainModule.class, ...})public interface MainComponent { void inject(Activity activity);}
MainComponent.java
@Singleton@Component(modules = { MainModule.class, ...})public interface MainComponent { void inject(Activity activity);}
MainComponent.java
@Singleton@Component(modules = { MainModule.class, ...})public interface MainComponent { void inject(Activity activity);}
MainComponent.java
@Singleton@Component(modules = { MainModule.class, ...})public interface MainComponent { void inject(Activity activity);}
MainComponent.java
@Singleton@Component(modules = { MainModule.class, ...})public interface MainComponent { void inject(Activity activity);}
MainComponent.java
@Singleton@Component(modules = { MainModule.class, ...})public interface MainComponent { void inject(Activity activity);}
MainComponent.java
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); }}
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); }}
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); }}
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); }}
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); }}
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); }}
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); }}
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); }}
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); }}
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; }}
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; }}
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; }}
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; }}
Activity
Application
Activity
Application
Component
Activity
Application
Component
Activity
MainModule
Application
Component
Activity
Modules...MainModule
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); }}
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); }}
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); }}
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); }}
Repository
CacheApi
Repository
MockCacheMockApi
Api Cache
Examples
github.com/marcellogalhardo/events
github.com/marcellogalhardo/locations
Questions?
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