Explain the concept of inversion of control and its application in the Spring framework

Inversion of Control (IoC) is a principle where the control of creating and binding objects is delegated to an external container or framework, rather than being implemented directly in the application code. This reduces component coupling and increases flexibility.

In Spring, IoC is implemented through a container that manages the lifecycle and dependencies of objects (beans). Instead of manually creating objects, the developer describes dependencies, and Spring automatically injects the required components.

Example of dependency injection via annotation:

@Component
public class UserService {
    private final UserRepository userRepository;

    @Autowired
    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
}

Here, Spring creates and injects an instance of UserRepository into UserService, managing dependencies automatically.