Dagger2 + ViewModel +存储库

Question

I am new to Dagger 2 and trying to implement it in Kotlin. Here i am trying to inject my repository object into viewmodel. I am successfully able to inject it this way

public class LoginViewModel @Inject constructor(var mApplication: Application, var repository: LoginRepository) :
ViewModel() {

This is how my repository looks like

 class LoginRepository @Inject constructor(val retrofit: APICallInterface) {

This is how my module looks like

@Module
class BaseModule {

@Provides
fun getRetrofit(): APICallInterface {

    return Retrofit.Builder()
        .baseUrl("https://samples.openweathermap.org/data/2.5/")
        .addConverterFactory(GsonConverterFactory.create())
        .build().create(APICallInterface::class.java)
}

What i am unable to understand is how Dagger 2 is able to provide an object for repository as i have not mentioned it in any module with @Provides annotation.

I have tried following many blogs and few stckoverflow questions available here but none of them is solving my doubt.

Any help/explanation will be appreciated.

Answer 1

What i am unable to understand is how Dagger 2 is able to provide an object for repository as i have not mentioned it in any module with @Provides annotation.

You're using constructor injection by annotating the constructor with @Inject :

[ @Inject ] Identifies injectable constructors, methods, and fields.

So, by adding the annotation, Dagger becomes aware of the constructor and knows how to create the object when needed.

 class LoginRepository @Inject constructor(..)

If your constructor wouldn't have the annotation on it then you'd need a @Provides annotated method in a module so that Dagger can access the dependency, but you should use @Provides annotated methods primarily for objects that need additional setup and/or initialization.