Handling Circular Dependencies in Spring with @Autowired and Constructor Injection
I'm working on a personal project and I'm trying to debug This might be a silly question, but I'm facing an issue with circular dependencies in my Spring application while using constructor injection. My setup involves two services, `UserService` and `NotificationService`, where `UserService` depends on `NotificationService` for sending notifications, and `NotificationService` depends on `UserService` for fetching user details before sending notifications. When I start the application, I receive a `BeanCurrentlyInCreationException` stating that `UserService` is currently in creation while trying to autowire `NotificationService`. I have tried resolving this by switching to field injection, but that doesn’t align with my goal of following best practices for constructor injection. Here are the relevant snippets of my code: ```java @Service public class UserService { private final NotificationService notificationService; @Autowired public UserService(NotificationService notificationService) { this.notificationService = notificationService; } public void registerUser(User user) { // registration logic notificationService.sendNotification(user); } } @Service public class NotificationService { private final UserService userService; @Autowired public NotificationService(UserService userService) { this.userService = userService; } public void sendNotification(User user) { // notification logic involving userService } } ``` I attempted to resolve the circular dependency by using Spring's `@Lazy` annotation on one of the service constructors, but it felt like a workaround rather than a proper solution. I also explored using `@PostConstruct` for one of the services but still encountered the same issue during application startup. What would be the best practice to handle circular dependencies in a way that maintains proper design principles? Any suggestions or patterns that could help avoid this situation would be greatly appreciated. I recently upgraded to Java LTS. Any pointers in the right direction?