Problems with singletons when using component dependencies

Question

I\'m having a problem in understanding why the following code doesn\'t work.

I have following project structure:

@Component(modules = CCModule.class)         


        

Answer 1

You should put @Singletonto CComponent class declaration.

@Singleton
@Component(modules = CCModule.class) 
public interface CComponent {
    XXX getXXX();
}

Explanation is in error message: CComponent is unscoped, @Singleton is a scope. Dagger 2 does not allow unscoped components to use modules with scoped bindings.
However, now you will get the following error:

AComponent (unscoped) cannot depend on scoped components:
@Component(dependencies = CComponent.class, modules = AModule.class)

Unscoped components cannot have scoped dependencies. So you need to make AComponent scoped. To do this create custom AScope annotation.

@Scope
@Retention(RetentionPolicy.RUNTIME)
public @interface AScope {
}

And annotate with it AComponent:

@AScope
@Component(dependencies = CComponent.class, modules = AModule.class)
public interface AComponent {
}

These are new requirements appeared in latest snapshot release. It was discussed in corresponding issue and may still be changed.