Top 15 Spring Boot Interview Questions and Answers

Top 15 Spring Boot Interview Questions – 2025

Spring Boot is one of the most demanded frameworks for Java backend development. Whether you're interviewing for TCS, Infosys, or a product-based company, these Spring Boot questions will help you prepare like a pro. Here are 15 questions with detailed explanations for developers with 1–2 years of experience.

Q1. What is Spring Boot?

Answer: Spring Boot is a Java-based open-source framework built on top of the Spring Framework. It helps developers create stand-alone, production-ready Spring applications with minimal configuration. Its key features include:

Auto-configuration
Embedded servers (Tomcat, Jetty)
Starter dependencies
Production-ready tools (Actuator, Metrics, etc.)

Example: You can create a REST API within minutes by using @RestController and spring-boot-starter-web — no need for external web server deployment.

Q2. What is the role of @SpringBootApplication annotation?

Answer: This annotation is a shortcut that combines:

@Configuration – Marks the class as a source of bean definitions
@EnableAutoConfiguration – Enables auto-configuration
@ComponentScan – Enables scanning for components

It bootstraps the Spring Boot application with one annotation on the main class.

Q3. How does Spring Boot auto-configuration work?

Answer: Spring Boot checks the classpath for libraries (like Spring Web, JPA, etc.) and configures beans automatically using @Conditional annotations. The logic is defined in spring.factories files under META-INF.

Auto-configuration saves time by removing boilerplate and reduces manual bean registration.

Q4. What are starter dependencies in Spring Boot?

Answer: Starter dependencies are pre-configured sets of dependencies. For example, spring-boot-starter-web includes everything needed to build REST APIs: Spring MVC, Tomcat, Jackson, etc. They allow rapid setup of modules without worrying about individual versions.

Q5. What is Spring Boot Actuator?

Answer: Actuator exposes production-ready endpoints like:

/actuator/health – Health status
/actuator/info – App metadata
/actuator/metrics – Performance metrics

It's useful for monitoring and management in cloud or microservices environments.

Q6. What is the difference between Spring and Spring Boot?

Spring Framework: Requires manual configuration, external servlet container, and verbose XML or Java config.
Spring Boot: Auto-configures everything, uses embedded servers, and offers a production-ready skeleton with minimal effort.

Q7. What is the use of application.properties or application.yml?

Answer: These files are used to configure server port, database credentials, logging, caching, etc. Example:

server.port=8081
spring.datasource.url=jdbc:mysql://localhost:3306/mydb

Q8. What is the purpose of @RestController?

Answer: @RestController is a specialized version of @Controller that returns JSON/XML responses directly. It combines @Controller + @ResponseBody. Used in building RESTful APIs.

Q9. How do you connect a database in Spring Boot?

Answer: Add the DB driver dependency (e.g. MySQL), then configure spring.datasource.* properties in application.properties. Spring Boot will auto-configure DataSource, EntityManager, and transaction management.

Q10. How to handle exceptions in Spring Boot?

Answer: Use @ControllerAdvice with @ExceptionHandler methods to handle exceptions globally. You can return custom error responses in a consistent format across your application.

Q11. What is @Component, @Service, and @Repository?

@Component: Generic bean
@Service: Marks business logic layer
@Repository: Marks data access layer with automatic exception translation

Q12. What is Spring Boot DevTools?

Answer: DevTools provides automatic restarts, live reload, and better logging. It helps speed up development by reflecting changes without full application restart.

Q13. Difference between @ComponentScan and @EnableAutoConfiguration?

@ComponentScan: Scans packages for Spring-managed components
@EnableAutoConfiguration: Triggers Spring Boot’s auto-configuration based on classpath dependencies

Q14. What is Spring Boot CLI?

Answer: Spring Boot CLI allows you to run Spring Boot apps written in Groovy. It's useful for rapid prototyping and scripting without creating a full Maven/Gradle project.

Q15. How do you test Spring Boot applications?

Answer: Use:

@SpringBootTest for full context testing
@WebMvcTest for controller testing
@DataJpaTest for JPA layer

Also use JUnit5 + Mockito for unit testing. Embedded H2 DB is great for integration tests.

✅ Final Interview Tips:

Explain how you used Spring Boot in real projects
Understand annotations and auto-configuration deeply
Be prepared to write and debug REST APIs live

📅 Last Updated: 15 May 2025
📎 #SpringBoot #JavaBackend #InterviewQuestions2025 #SpringInterview

TCS Java Interview | Java | Spring Boot | Microservices | Database

TCS Java Interview | Java | Spring Boot | Microservices | Database This post is based on a Java backend developer interview simulation and provides direct transcript-based answers to help you prepare for similar interviews. 📺 This interview scenario was inspired by a video from the YouTube channel: CloudTech . 🔗 Watch the full video here: https://www.youtube.com/watch?v=yVj2EgwZxk4 1. Can you introduce yourself and talk about your tech stack and domains? I have around 4.5 years of experience working as a Java developer. My core expertise is in Java and developing REST APIs using Spring Boot. I also have basic knowledge of microservices architecture. On the database side, I work with SQL and Oracle. Additionally, I have exposure to UI technologies like Angular, HTML, and CSS, but they are secondary skills. My primary focus is backend Java development. 2. Which version of Java are you currently working on? We are currently using Java 8 but are in the process of upgr...

Interview Yatra

Search This Blog