Java: Observer Pattern

The Observer Pattern allows for dynamic addition or removal of notification services without altering the core checkout logic.

In an e-commerce checkout system, the Observer Pattern can be used to manage different notification services, such as email, SMS, or push notifications. By implementing the Observer Pattern, you can add or remove notification services independently of the checkout process. This decouples the core logic from the notification details, leading to a more flexible and maintainable system. For example, if your checkout system broadcasts an event every time an order is completed, observers like EmailService or SMSService will listen for this event and act accordingly. This setup allows you to introduce a new notification channel, such as a mobile app alert, without modifying the checkout code directly.