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Top 20 Spring Boot Interview Questions for Experienced Developers

Top 20 Spring Boot Interview Questions for Experienced Developers




Preparing for a Spring Boot interview? Whether you work in product-based or service companies, these 20 carefully crafted questions are based on real-world scenarios and are ideal for Java backend developers with 2+ years of hands-on Spring Boot experience.

1. What is Spring Boot and how is it different from Spring?

Answer: Spring Boot simplifies Spring application setup with auto-configuration, embedded servers, and minimal XML. It is built on top of Spring and makes development faster and easier.

2. What are the key advantages of Spring Boot?

Answer:

  • Auto Configuration
  • Embedded servers like Tomcat/Jetty
  • No boilerplate XML
  • Production-ready tools via Actuator
  • Faster deployment lifecycle

3. What is @SpringBootApplication?

Answer: It combines @Configuration, @EnableAutoConfiguration, and @ComponentScan. It marks the main class of your Spring Boot app.

4. How does Spring Boot's auto-configuration work?

Answer: It uses @EnableAutoConfiguration and classpath analysis to configure beans automatically, based on dependencies using conditional annotations.

5. What is the role of application.properties or .yml?

Answer: They hold application configuration like port, DB URL, logging level, and profile setup.

6. Difference between @Component, @Service, and @Repository?

Answer:

  • @Component – Generic stereotype for a Spring-managed component.
  • @Service – Marks business logic layer.
  • @Repository – Used in DAO layer with built-in exception translation.

7. How is dependency injection done in Spring Boot?

Answer: Using @Autowired or constructor injection. Constructor injection is preferred for better testability and immutability.

8. What are Spring Profiles?

Answer: They allow different configurations for different environments like dev, test, and prod. You activate them via spring.profiles.active.

9. What is Spring Boot Actuator?

Answer: It provides endpoints to monitor application health, metrics, info, and more.

10. How do you configure a database connection in Spring Boot?

Answer: Use properties like spring.datasource.url, username, and password in application.properties. Spring Boot auto-configures DataSource and JPA.

11. What is @RestController?

Answer: It's a shortcut for @Controller + @ResponseBody, used to create RESTful web services.

12. Difference between @RequestParam and @PathVariable?

Answer:

  • @RequestParam – used for query params (e.g., /api?id=1)
  • @PathVariable – used for URI segments (e.g., /api/1)

13. What is Spring Data JPA?

Answer: It simplifies database access using interfaces like JpaRepository. No need to write boilerplate CRUD queries.

14. How do you handle exceptions in Spring Boot REST APIs?

Answer: Use @ControllerAdvice with @ExceptionHandler to handle exceptions globally and return custom JSON responses.

15. What embedded servers does Spring Boot support?

Answer: Tomcat (default), Jetty, and Undertow. You can switch by changing dependencies.

16. How do you secure REST APIs in Spring Boot?

Answer: Using Spring Security with basic auth, JWT tokens, role-based access control, and endpoint whitelisting.

17. What is @Transactional?

Answer: It manages transactions automatically. If a method fails, it rolls back DB changes.

18. How do you write unit and integration tests?

Answer: Use @SpringBootTest, @MockBean, JUnit 5, and Mockito for mocking. Use @WebMvcTest for controller tests.

19. Difference between Spring Boot and Spring MVC?

Answer: Spring Boot includes Spring MVC, but adds auto-configuration, embedded servers, and faster bootstrapping. Spring MVC requires manual configuration.

20. How do you monitor Spring Boot applications?

Answer:

  • Actuator endpoints like /health, /metrics
  • Integration with Prometheus + Grafana
  • Spring Boot Admin
  • ELK stack (Elasticsearch, Logstash, Kibana)

🔥 Final Tips:

  • Always explain based on your real project experience
  • Mention tools like Postman, Jenkins, Git if used
  • Be clear on your role in the implementation

📅 Last Updated: 20 May 2025
📌 Bookmark InterviewYatra.com for the best Java + Spring Boot interview prep.

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