What is the role and advantages of using dependency injection in the Spring Framework?

Dependency Injection (DI) in the Spring Framework plays a key role in managing dependencies between application components.

Advantages of using DI:

• Loosening coupling: components do not create their dependencies directly, which simplifies replacement and testing.
• Simplifying testing: mocks or stubs can be easily substituted for real dependencies.
• Managing object lifecycle: the Spring container creates and manages objects, reducing the likelihood of errors.
• Increasing modularity and reusability of code.

Example of using DI with the @Autowired annotation:

@Component
public class UserService {
    private final UserRepository userRepository;

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

    // service methods
}

Here, Spring automatically injects the required UserRepository bean into UserService.