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
   

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2. @marcellogalhardo
   @marcellogalhardo
   @MarcelloGalhard
   marcello.galhardo@gmail.com
   /marcellogalhardo
   Android Dev BR
   slack.androiddevbr.org
   

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3. Do you know...
   ...inversion of control?
   

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4. Do you know...
   ...inversion of control?
   ...Dagger?
   

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5. Why should I use
   Dependency Injection?
   

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6. Easy reuse of
   components
   

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7. Safer and
   easier
   refactoring
   

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8. Easier testing
   

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9. Activity
   

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10. Presenter
    Activity
    

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11. Presenter
    Repository
    Activity
    

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12. Presenter
    Repository
    Activity
    Api
    

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13. Presenter
    Repository
    Activity
    Cache
    Api
    

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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
    

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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
    

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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
    

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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
    

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18. ● Too much boilerplate
    code;
    Problems!
    

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19. ● Too much boilerplate
    code;
    ● Hard to maintain the
    dependency graph.
    Problems!
    

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20. Let's talk about Dagger
    

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21. Dagger 2
    ● No Reflection;
    

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22. Dagger 2
    ● No Reflection;
    ● Code generated at build
    time;
    

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23. Dagger 2
    ● No Reflection;
    ● Code generated at build
    time;
    ● Easy to debug;
    

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24. Dagger 2
    ● No Reflection;
    ● Code generated at build
    time;
    ● Easy to debug;
    ● Easy to maintain the
    dependency graph.
    

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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"
    }
    

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26. @Singleton
    @Component(modules = {
    MainModule.class,
    ...})
    public interface MainComponent {
    void inject(Activity activity);
    }
    MainComponent.java
    

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27. @Singleton
    @Component(modules = {
    MainModule.class,
    ...})
    public interface MainComponent {
    void inject(Activity activity);
    }
    MainComponent.java
    

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28. @Singleton
    @Component(modules = {
    MainModule.class,
    ...})
    public interface MainComponent {
    void inject(Activity activity);
    }
    MainComponent.java
    

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29. @Singleton
    @Component(modules = {
    MainModule.class,
    ...})
    public interface MainComponent {
    void inject(Activity activity);
    }
    MainComponent.java
    

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30. @Singleton
    @Component(modules = {
    MainModule.class,
    ...})
    public interface MainComponent {
    void inject(Activity activity);
    }
    MainComponent.java
    

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31. @Singleton
    @Component(modules = {
    MainModule.class,
    ...})
    public interface MainComponent {
    void inject(Activity activity);
    }
    MainComponent.java
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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;
    }
    }
    

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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;
    }
    }
    

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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;
    }
    }
    

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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;
    }
    }
    

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45. Activity
    

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46. Application
    Activity
    

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47. Application
    Component
    Activity
    

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48. Application
    Component
    Activity
    MainModule
    

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49. Application
    Component
    Activity
    Modules...
    MainModule
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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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);
    }
    }
    

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54. Repository
    Cache
    Api
    

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55. Repository
    MockCache
    MockApi
    Api Cache
    

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56. Examples
    

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57. github.com/marcellogalhardo/events
    

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58. github.com/marcellogalhardo/locations
    

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59. Questions?
    

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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
    

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