How to create an object using constructor injection?

Question

How would I create an instance of Dog with a component which provides Cat.

public final class Dog {     private final Cat mCat;     public final static String TAG = "Dog";      @Inject public Dog(Cat cat) {         mCat = cat;         Log.e(TAG, "Dog class created");     } } 

After experimenting with Dagger 2 for a while I have no idea how to use constructor injection – a hint would be nice, thanks.

Edit:
Whats wrong with the question? After using Dagger 2, following several tutorials and reading the official documentation I have no clue how to use the constructor injection feature, that's why I ask here. Instead of injecting the Cat dependency into Dog with @Inject I could write a DogModule providing a Dog object, but then Dog would be just a regular Java class. Field injection works great (there are a lot of examples showing how to use it) but what do I need to do to use constructor injection?

Answer 1

To create an object using the Dagger 2 constructor injection feature you need to add a method to a component which provides a Cat class.

@Component(     dependencies = ApplicationComponent.class,     modules = CatModule.class) public interface ActivityComponent {     void inject(final CatActivity a);     // objects exposed to sub-components     Cat cat();     Dog dog(); } 

An instance of Dog can then be retrived by calling [Component].dog().

final ActivityComponent comp = DaggerActivityComponent.builder()             .applicationComponent(app.getApplicationComponent())             .build();  final Dog d = comp.dog();