What is a Subcomponent in Dagger?

A Subcomponent in Dagger is a component that extends the functionality of a parent component by providing dependencies defined in its modules, as well as dependencies provided by the parent component.

Key features:

• Inherits dependencies: The Subcomponent has access to all dependencies provided by the parent component.
• Extends the dependency graph: It adds its own modules and, consequently, its own dependencies.
• Limited scope: Its lifecycle is usually shorter than that of the parent component and is tied to a specific context or type.
• Used for modularity: It allows dividing the dependency graph into smaller, manageable parts.

Creating a Subcomponent:

1. Declare the Subcomponent:

   interface FeatureComponent {
       // Methods to provide dependencies
   
       @Subcomponent.Factory
       interface Factory {
           fun create(): FeatureComponent
       }
   }
   

2. Bind the Subcomponent to the parent component:

   @Component(...)
   interface AppComponent {
       fun featureComponent(): FeatureComponent.Factory
   }
   

Using the Subcomponent:

val appComponent = DaggerAppComponent.create()
val featureComponent = appComponent.featureComponent().create()