60+ Mostly Asked Spring Boot Interview Questions for 3+ Yrs

Here is a list of 60+ Spring Boot interview questions for candidates with 3+ years of experience:

1. What is Spring Boot?

Ans: Spring Boot is an open-source Java framework built on top of the Spring Framework. It helps developers to create easily production-ready, stand-alone, and microservice-based applications with less effort. It provides a various dependency that helps to integrated desired library in the project very easily by just adding in the POM.xml file.

2. Explain the advantages of using Spring Boot.

Ans:

Advantages of Spring Boot:

Rapid Development: Spring Boot reduces the need for writing a lot of boilerplate code. It allowing developers to focus on business logic rather than dependency configuration.
Microservices: Spring boot is the well-suited and popular java framework for building microservices applications. It is possible because of its modular and self-contained nature.

Auto-Configuration: It automatically configures application components based on dependencies present in the classpath.
Embedded Servers: Spring Boot comes with embedded servers like Tomcat, Jetty, and Undertow, making deployment easier. We need only pom.xml file configurations.
Production-Ready: Built-in features like health checks, metrics, and security make applications ready for production deployment.

Easy Testing: Spring Boot supports various testing frameworks, making unit and integration testing simpler.

3. What are the different ways to create a Spring Boot application?

Ans: Different Ways to Create a Spring Boot Application:

Using Spring Initializr: You can use the Spring Initializr web tool to generate a Spring Boot project with the required dependencies. Web tool link is https://start.spring.io/

Using Spring Boot CLI: The Spring Boot CLI stands for command line interface, that allows you to quickly create Spring Boot applications using the command line.
Using IDEs: With the help of IDEs (Integrated Development Environments) like Eclipse, IntelliJ IDEA, and Visual Studio Code you can also create spring boot applications. You need plugins to create Spring Boot projects.
Manually: You can manually set up a Spring Boot project by adding the required dependencies and configurations.

4. How does Spring Boot Simplify the Configuration Process?

Ans: Spring Boot simplifies the configuration process in many ways for the developer. It makes setup and configuration process easier for developers. Some key features that simplify the configuration process are Auto-Configuration, Starter Dependencies, Default Configuration, Property Binding, Profile Management, Embedded Servers, Production-Ready Actuators, Command-Line Interface (CLI) etc.

5. What is the purpose of the @SpringBootApplication annotation?

Ans: @SpringBootApplication annotation is used to mark the main class of a Spring Boot application. It is basically a starting point of the spring boot applications. It combines three annotations: @SpringBootConfiguration, @EnableAutoConfiguration, and @ComponentScan.

6. Explain the auto-configuration feature in Spring Boot.

Ans: Spring Boot’s auto-configuration automatically configures Spring beans based on the libraries and dependencies detected on the classpath. It eliminates the need for manual bean configuration, making the application setup more convenient and faster.

7. How can you customize the default behavior of Spring Boot?

Spring Boot default behavior can be customized by the providing your own configuration classes, properties, and beans. Or we can also customized by overriding auto-configured beans or properties, as per our specific needs of the application.

8. What is Spring Boot Actuator?

Spring Boot Actuator is a set of monitoring tool provided by the spring boot. It helps in production to monitor the spring boot application health. It helps to monitor and manage applications by exposing various endpoints, such as health, metrics, info, and more.

9. How do you enable Actuator endpoints in a Spring Boot application?

Actuator endpoints can be enabled by adding the spring-boot-starter-actuator dependency to your project’s pom.xml file. The endpoints are enabled by default, but you can configure which ones to expose and their properties.

10. What are some commonly used Actuator endpoints?

<br>/actuator/health: Provides information about the health of the application.

/actuator/metrics: Exposes application metrics.

/actuator/info: Displays custom application information.

/actuator/env: Shows properties from the application’s environment.

11. How can you secure Actuator endpoints in Spring Boot?

Actuator endpoints are sensitive by default. If not secure, any one can access it. So for that reason they require appropriate security configuration. You can secure them by configuring authentication and authorization settings in the application’s configuration files.

12. What is the purpose of the @RestController annotation?

In Spring Boot Framework, @RestController annotation is used to indicate that a class is a specialized version of the @Controller class. It is used in building RESTful web services. It combines @Controller and @ResponseBody, indicating that the methods in the class return the response body directly. List of the @RestController annotations purpose are Creating REST Endpoints, Response Serialization, No Need for @ResponseBody etc.

13. Explain the difference between @Controller and @RestController in Spring Boot.

In Spring Boot, both @Controller and @RestController are used to handle HTTP requests and build web applications.

@Controller:

The @Controller annotation is used to mark a class as a Spring MVC controller.

Controllers are responsible for handling incoming HTTP requests, processing them, and returning an appropriate response. They are commonly used to create dynamic web pages where the response might include HTML templates and view rendering.
Methods within a @Controller class are typically responsible for returning logical view names, which are resolved to actual view templates for rendering.

@RestController:

The @RestController annotation is a specialized version of @Controller that is tailored for building RESTful web services.
Classes annotated with @RestController still handle incoming HTTP requests, but their primary focus is on returning data in various formats like JSON or XML, rather than rendering views.
Methods within a @RestController class automatically have the @ResponseBody annotation applied to them, meaning that the return values of these methods are directly serialized into the response body.

14. What is Spring Data JPA?

Spring Data JPA is a subproject of the Spring Framework. It provides a high-level abstraction over the Java Persistence API (JPA) standard for working with relational databases. It simplifies the process of interacting with databases and reduces the amount of boilerplate code required for common database operations like CRUD operations and querying databases.

15. How do you define database connections in Spring Boot?

Database connections in Spring Boot can be configure properties in the application.properties or application.yml file. Spring Boot provides auto-configuration for various databases, and you can also customize the configuration.

application.properties

# Database configuration
spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=myuser
spring.datasource.password=mypassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

application.yml

# Database configuration
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mydb
    username: myuser
    password: mypassword
    driver-class-name: com.mysql.cj.jdbc.Driver

16. Explain the use of Spring Boot Starter POMs.

Starter POMs are a set of convenient dependency descriptors that can be included in your project’s build configuration (like pom.xml) to automatically manage the dependencies required for specific functionalities, such as web, data, security, etc.

17. How can you handle exceptions in a Spring Boot application?

18. What is the purpose of the @ComponentScan annotation?

19. Explain the concept of dependency injection in Spring Boot.

20. What is the difference between @Autowired and @Inject annotations?

21. How do you handle form submissions in Spring Boot?

22. Explain the concept of profiles in Spring Boot.

23. How can you implement caching in a Spring Boot application?

24. What is the purpose of the @Scheduled annotation?

25. Explain the role of Spring Boot starters in the development process.

26. What is the purpose of the @EnableAutoConfiguration annotation?

27. How can you enable cross-origin requests in a Spring Boot application?

28. Explain the concept of Spring Boot Actuator metrics.

29. What is the purpose of the @Transactional annotation?

30. How can you implement security in a Spring Boot application?

31. Explain the role of the Spring Boot DevTools.

32. What is the purpose of the @RequestMapping annotation?

33. How can you enable HTTP compression in Spring Boot?

34. Explain the concept of internationalization in Spring Boot.

35. What is Spring Boot Data REST?

36. How can you enable Swagger documentation in a Spring Boot application?

37. Explain the purpose of the @Value annotation in Spring Boot.

38. What is the purpose of the @ConfigurationProperties annotation?

39. How can you perform unit testing in Spring Boot?

40. Explain the concept of application.properties in Spring Boot.

41. What is the purpose of the Spring Boot Actuator health check?

42. How can you implement distributed logging in a Spring Boot microservice architecture?

43. Explain the concept of Spring Boot starters and parent POMs.

44. What is the purpose of the @EnableCaching annotation?

45. How can you handle file uploads in Spring Boot?

46. Explain the use of the @Qualifier annotation in Spring Boot.

47. What is the purpose of the @Transactional annotation in Spring Boot?

48. How can you handle asynchronous tasks in a Spring Boot application?

49. Explain the purpose of the @RestControllerAdvice annotation.

50. What is the role of Spring Boot Actuator in monitoring and managing a Spring Boot application?

51. How can you implement OAuth2 authentication in a Spring Boot application?

52. Explain the purpose of the @PathVariable annotation in Spring Boot.

53. What is the purpose of the @Entity annotation in Spring Boot?

54. How can you configure a connection pool in Spring Boot?

55. Explain the purpose of the @Async annotation in Spring Boot.

56. What is the purpose of the Spring Boot Actuator info endpoint?

57. How can you implement rate limiting in a Spring Boot application?

58. Explain the concept of Spring Boot Actuator tracing.

59. What is the purpose of the @ResponseStatus annotation in Spring Boot?

60. How can you configure multiple data sources in a Spring Boot application?

Now, let’s move on to the interview clearing guide. Here are some tips to help you succeed in a Spring Boot interview:

Review the Basics: Ensure you have a strong understanding of the fundamental concepts of Spring Boot, including dependency injection, annotations, and inversion of control.

Hands-on Experience: Be prepared to discuss your experience working with Spring Boot. Showcase any relevant projects or assignments you have completed using the framework.
Understand Spring Boot Features: Familiarize yourself with key Spring Boot features such as auto-configuration, Actuator, data access with Spring Data JPA, security, and caching. Be ready to explain how you have utilized these features in your projects.
Demonstrate Problem-Solving Skills: Expect questions that require you to solve problems related to Spring Boot. Prepare yourself by practicing coding exercises and scenarios that involve troubleshooting and debugging.

Dive into Documentation: Take the time to explore the official Spring Boot documentation. Understand the various configuration options, available annotations, and best practices recommended by the framework.
Stay Up-to-Date: Keep yourself updated with the latest trends and advancements in Spring Boot. Stay informed about new releases, enhancements, and community-driven developments.
Prepare for Common Interview Questions: Review commonly asked interview questions and practice your answers. This will help you articulate your thoughts effectively during the interview.

Showcase your Practical Knowledge: Whenever possible, share examples from your previous projects where you have utilized Spring Boot effectively. Discuss the challenges you faced and how you overcame them.
Be Confident and Professional: Approach the interview with confidence and maintain a professional demeanor throughout. Display your enthusiasm for Spring Boot and your eagerness to learn and grow as a developer.
Ask Questions: At the end of the interview, don’t hesitate to ask questions about the company’s usage of Spring Boot, their development processes, or any other relevant topics. This demonstrates your interest in the role and your desire to understand the organization better.

Remember, preparation is key to success. By following these guidelines, you’ll be well-prepared to clear your Spring Boot interview with confidence. Good luck!