In the previous article, we explored how Java 8–17 features transformed modern application development. In this article, we’ll see how Spring Boot leverages those features to build scalable, event-driven microservices.
Question 1
Which Spring Cloud Function interface is most suitable for exposing the same business logic through REST, Kafka, and AWS Lambda?
A. Runnable
B. Function
C. Callable
D. Thread
✅ Answer
B. Function
Explanation
Spring Cloud Function allows a single Function<T,R> implementation to be deployed behind multiple adapters, enabling true write-once, deploy-anywhere business logic.
Question 2
Which Spring event mechanism is best suited for decoupling components within the same microservice?
A. REST
B. ApplicationEventPublisher
C. Kafka
D. Cron Scheduler
✅ Answer
B. ApplicationEventPublisher
Explanation
Spring Events enable loose coupling inside a single application without introducing external messaging infrastructure.
Question 3
Which annotation is commonly used to execute event listeners asynchronously?
A. @Component
B. @Async
C. @Autowired
D. @Configuration
✅ Answer
B. @Async
Explanation
Combining @Async with @EventListener allows event processing to occur in the background, improving response times for non-critical work such as notifications or audit logging.
Question 4
Why should business logic generally not be placed inside Controllers?
A. Controllers cannot access databases.
B. It violates separation of concerns and reduces testability.
C. Controllers run slower than Services.
D. Spring Boot does not allow it.
✅ Answer
B. It violates separation of concerns and reduces testability.
Explanation
Controllers should orchestrate HTTP requests. Business rules belong in the service layer, where they can be reused, tested, and exposed through multiple interfaces.
Question 5
Which Spring Boot feature automatically configures beans based on classpath dependencies?
A. BeanFactory
B. Auto Configuration
C. Reflection API
D. Bean Validation
✅ Answer
B. Auto Configuration
Explanation
Spring Boot’s auto-configuration reduces boilerplate by configuring common infrastructure components automatically.
Question 6
Why should long-running tasks be avoided inside @PostConstruct?
A. They consume heap memory.
B. They delay application startup and may cause probe failures.
C. They disable dependency injection.
D. They block Garbage Collection.
✅ Answer
B. They delay application startup and may cause probe failures.
Explanation
Heavy initialization inside @PostConstruct can delay readiness, causing Kubernetes Startup or Readiness Probes to fail.
Question 7
Which propagation level creates a completely new transaction?
A. REQUIRED
B. SUPPORTS
C. REQUIRES_NEW
D. MANDATORY
✅ Answer
C. REQUIRES_NEW
Explanation
REQUIRES_NEW suspends the current transaction and starts a new one, making it useful for audit logging and independent persistence operations.
Question 8
Which Spring Boot feature is commonly used to expose application health for Kubernetes?
A. Spring Security
B. Spring Actuator
C. Spring Batch
D. Spring Data
✅ Answer
B. Spring Actuator
Explanation
Spring Boot Actuator provides health endpoints that integrate directly with Kubernetes Startup, Readiness, and Liveness Probes.
Question 9
Why are application events preferred over direct service calls for non-critical processing?
A. They increase CPU speed.
B. They reduce coupling and improve extensibility.
C. They replace REST APIs.
D. They eliminate transactions.
✅ Answer
B. They reduce coupling and improve extensibility.
Explanation
Events allow additional listeners—such as audit, notification, or analytics—to be added without modifying existing business logic.
Question 10
What is the biggest advantage of Spring Cloud Function in modern microservices?
A. It replaces Spring Boot.
B. It eliminates REST controllers.
C. It decouples business logic from the transport mechanism.
D. It automatically scales Kubernetes Pods.
✅ Answer
C. It decouples business logic from the transport mechanism.
Explanation
The same business function can be invoked via HTTP, messaging platforms like Kafka or Solace, or serverless platforms such as AWS Lambda. This separation improves portability, reuse, and long-term maintainability.
Summary
Spring Boot builds on Java’s functional programming capabilities to create modular, testable, and transport-agnostic microservices. Understanding how Functional Interfaces, Spring Events, Cloud Function, transactions, and Actuator fit together is essential for senior developers designing production-grade systems.
