Can you explain the mechanism of annotations in the Dagger library?

In Dagger, annotations are used to define dependencies and manage their injection (dependency injection). Main annotations:

• @Inject — marks constructors, fields, or methods where Dagger should inject dependencies.
• @Module — a class that provides dependencies via methods annotated with @Provides.
• @Component — an interface that connects modules and injection points, creating a dependency graph.

The mechanism works as follows: during compilation, Dagger analyzes annotated elements, generates code that creates and links objects considering dependencies, avoiding manual creation and passing of dependencies.

Example:

class Engine {
    @Inject
    Engine() {}
}

@Module
class CarModule {
    @Provides
    Car provideCar(Engine engine) {
        return new Car(engine);
    }
}

@Component(modules = CarModule.class)
interface CarComponent {
    Car getCar();
}

Here, Dagger will automatically create an Engine object and inject it into Car.