patrykpoborca

public class CleanArchitectureApplication extends Application{

    private static BaseComponent sBaseComponent;

    @Override
    public void onCreate() {
        super.onCreate();

        ApplicationComponent applicationComponent = DaggerApplicationComponent
                                        .builder()

patrykpoborca

public BaseComponent build() {  
  if (localModule == null) {
    this.localModule = new LocalModule();
  }
  if (networkModule == null) {
    this.networkModule = new NetworkModule();
  }
  if (applicationComponent == null) {
    throw new IllegalStateException("applicationComponent must be set");
  }

patrykpoborca

@Component(dependencies = {BaseComponent.class})
public interface ActivityInjectorComponent {

    void inject(MainActivity activity);
}

patrykpoborca

public class MainActivity extends AppCompatActivity {

    @Inject
    TweeterApi tweeterApi;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

patrykpoborca

//dagger 2 implementation of a module
@Module
public class MyModule {

    @Provides
    public MyDependency providesMyDependency(){
        return new MyDependency();
    }

    @Provides

patrykpoborca

@Inject //Constructor Injection
public AnotherClass(MyDependency myDependency){
}

@Inject //Field Injection
MyDependency myDependency;

@Inject //Method Injection
public void myMethod(MyDependency myDependency){

patrykpoborca

public class AnotherClass {

   private final MyClass myClass;

   public AnotherClass(MyClass myClass){
      this.myClass = myClass;
   }
}

public class Main{

patrykpoborca

public class DependencyFactory{

   private static MyDependency myDependency;
   private static MyClass myClass;

   public static MyDependency providesMyDependency(){
      if(myDependency == null){
         myDependency = new MyDependency();
      }
      return myDependency;

patrykpoborca

public class AnotherClass{

   private final MyClass myClass;

   //Good!
   public AnotherClass(MyClass myClass){
      this.myClass = myClass;
   }
}

patrykpoborca

public class MyDependency {}

public class MyClass {
   private MyDependency dependency;

   public MyClass(MyDependency myDependency){
      this.dependency = myDependency;
   }
}