We have seen a basic DI implementation, now it is time to understand how injection works in Guice. Let's rewrite the example of a notification system using Guice, and along with that, we will see several indispensable interfaces and classes in Guice. We have a base interface called NotificationService, which is expecting a message and recipient details as arguments:
public interface NotificationService {
boolean sendNotification(String message, String recipient);
}
The SMSService concrete class is an implementation of the NotificationService interface. Here, we will apply the @Singleton annotation to the implementation class. When you consider that service objects will be made through injector classes, this annotation is furnished to allow them to understand that the service class ought to be a singleton object. Because...
