Top 50 Spring Boot Interview Questions and Answers
Spring Boot is a popular module of Spring Framework that provides RAD (Rapid Application Development) feature to create stand-alone Spring applications that can be started using java -jar command. It simplifies the configuration and dependency management of Spring applications by using conventions and starter dependencies. It also offers several features such as Spring Actuator, Spring Initializer, and Spring Boot CLI. You can learn the best practices of Spring Boot with Spring Framework courses and prepare yourself for your next interview.
In this article, we have listed some of the most common Spring Boot interview questions. The questions are divided into two categories: general and experienced. The general Spring Boot questions are suitable for beginners and freshers, while the experienced questions are for professionals who have worked with Spring Boot for some time.
General Spring Boot Interview Questions
Q1. What is Spring Boot and mention the need for it?
Answer: This is one of the most common Spring Boot interview questions. Spring Boot is a module of Spring Framework that helps you create stand-alone Spring applications quickly and easily. It does this by providing auto-configuration and starter dependencies that reduce the boilerplate code. This is one of the basic spring boot interview questions that you may encounter.
Q2. What are the advantages of Spring Boot?
Answer: Spring Boot has many advantages such as:
Faster development and deployment
Less configuration and dependency management
Embedded servers and executable JAR files
Various features and tools for testing, debugging, monitoring,
External configuration sources and profiles
Q3. What are the disadvantages of Spring Boot?
Answer: Spring Boot has some disadvantages such as:
Dependency conflicts or version mismatches
Hidden details or logic of Spring framework
Not suitable for complex or legacy applications
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Q4. What are starter dependencies in Spring Boot?
Answer: Starter dependencies are a set of dependencies that include everything you need to start a specific type of application with Spring Boot. For example, spring-boot-starter-web includes all the dependencies for web development. This is one of the common Java Spring Boot interview questions that you may face.
Q5. What is auto-configuration in Spring Boot?
Answer: Auto-configuration is a feature of Spring Boot that automatically configures your application based on the dependencies that you have added. For example, if you have added spring-boot-starter-web, then Spring Boot will configure a web application with a Tomcat server, Jackson library, and validation library. This is one of the important spring boot interview questions for experienced developers.
Q6. How do you create a Spring Boot application?
Answer: There are several ways to create a Spring Boot application, such as:
Spring Initializer web tool
Spring Boot CLI
IDE like Eclipse, IntelliJ
Maven/Gradle with parent POM/plugin.
Q7. How do you run a Spring Boot application?
Answer: There are several ways to run a Spring Boot application, such as:
java -jar for executable JAR
mvn spring-boot:run or gradle bootRun
IDE run/debug
Spring Boot CLI with Groovy/Java.
Q8. How do you configure a Spring Boot application?
Answer: There are several ways to configure a Spring Boot application, such as:
Files: application.properties/yml
Env vars or CLI args
@Configuration classes or @Bean methods
@Value or @ConfigurationProperties.
Q9. What is Spring Actuator and what are its benefits?
Answer: Spring Actuator is a feature of Spring Boot that provides various endpoints for monitoring and managing your application. Some of the benefits of Spring Actuator are:
It provides useful information about the health, metrics, mappings, beans, env, configprops of your application.
It allows you to perform various operations on your application, such as shutting down, changing log levels, refreshing properties,
It supports various formats and protocols for accessing the endpoints, such as HTTP, JMX, HAL browser,
It allows you to customise or extend the endpoints according to your needs.
Q10. What are profiles in Spring Boot and how do you use them?
Answer: This type of Spring Boot questions are easy to learn. Profiles are a way of grouping configuration properties and beans that are only activated under certain conditions. This is one of the basic spring boot interview questions.
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Spring Boot Interview Questions for Experienced
Q11. What are some of the best practices for using Spring Boot?
Answer: Some of the best practices for using Spring Boot are:
Use starters/auto-config
External config/profiles
Actuator for monitoring
Testing/debugging tools
Keep updated, resolve issues.
Q12. How do you test a Spring Boot application?
Answer: There are several ways to test a Spring Boot application, such as:
@SpringBootTest for context
@WebMvcTest for web
@DataJpaTest for data
@MockBean or @SpyBean for mocking.
Q13. How do you debug a Spring Boot application?
Answer: You can debug a Spring Boot application by using IDE, CLI, or tools like logging, tracing, actuator. This is one of the advanced Spring Boot interview questions for experienced professionals that you may encounter.
Q14. How do you secure a Spring Boot application?
Answer: You can secure a Spring Boot application by using Spring Security module that provides features like authentication, authorization, form login, OAuth2, JWT, and LDAP. You can also use annotations like @EnableWebSecurity, @PreAuthorize, @PostAuthorize to configure and secure your application.
Q15. How do you handle exceptions in a Spring Boot application?
Answer: This is one of the frequently asked Spring Boot interview questions and answers. You can handle exceptions in a Spring Boot application by using annotations like @ExceptionHandler, @ControllerAdvice, @ResponseStatus, or classes like ResponseEntityExceptionHandler, ErrorController, to define custom or global exception handlers or error pages.
Q16. How do you create RESTful web services in a Spring Boot application?
Answer: You can create RESTful web services in a Spring Boot application by using Spring MVC module that provides features like @RestController, @RequestMapping, @GetMapping, @PostMapping, annotations, ResponseEntity or @ResponseStatus class/annotation, @Valid or @Validated annotations, to define web controllers, request mappings, response status codes, validation rules,
Q17. How do you access data in a Spring Boot application?
Answer: You can access data in a Spring Boot application by using Spring Data project that supports modules and technologies like JPA, MongoDB, Redis, and Cassandra. You can also use annotations like @Entity, @Document, @Id, @Query, or interfaces like JpaRepository, MongoRepository, CrudRepository to define entities or documents, primary keys or queries, repositories or CRUD operations.
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Q18. How do you test a Spring Boot application?
Answer: This is one of the Spring Boot questions for experienced that will help you stand out in the interview. You can test a Spring Boot application by using Spring Boot Test module that provides annotations like @SpringBootTest, @WebMvcTest, @DataJpaTest, TestRestTemplate or MockMvc class, AssertJ or JUnit library to test different layers or components of your application such as web layer, data layer, service layer.
Q19. How do you deploy a Spring Boot application?
Answer: This is one of the Spring Boot interview questions experienced professionals that test your knowledge of deployment methods and tools. You can deploy a Spring Boot application by using various methods such as:
Executable JAR/WAR, use java -jar or web server (Tomcat, Jetty).
Spring Boot Maven/Gradle plugin: run, build Docker image, deploy to Kubernetes.
Spring Boot CLI: run Groovy/Java script or executable JAR.
Cloud platforms like Azure, AWS, Heroku for auto-scaling, and monitoring.
Q20. How do you monitor and manage a Spring Boot application?
Answer: This is one of the important spring boot interview questions for freshers as well as professionals that tests your knowledge of monitoring and management features and tools. You can monitor and manage a Spring Boot application by using Spring Boot Actuator module that provides features such as:
Add spring-boot-starter-actuator.
Endpoints like /health, /metrics, /info.
Configure via files or annotations.
Expose over HTTP, JMX, or SSH.
Use tools like Spring Boot Admin, Micrometer, Prometheus, and Grafana.
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Q21. How do you implement caching in a Spring Boot application?
Answer: This type of Spring Boot interview questions and answers for experienced professionals test your knowledge of caching features and providers. You can implement caching in a Spring Boot application by using Spring Cache module that provides features such as:
Add spring-boot-starter-cache.
Use @EnableCaching.
Annotations: @Cacheable, @CacheEvict, @CachePut.
Configure via files or annotations.
Q22. How do you implement asynchronous processing in a Spring Boot application?
Answer: This is one of the common Java Spring Boot interview questions that tests your knowledge of asynchronous processing features and components. You can implement asynchronous processing in a Spring Boot application by using various features and components provided by Spring Framework such as:
Using @EnableAsync, @Async.
Configuring via files or annotations.
CompletableFuture, ListenableFuture for async tasks and results.
Q23. How do you implement internationalisation in a Spring Boot application?
Answer: This is one of the Spring Boot interview questions for experienced people and freshers alike that tests your knowledge of internationalisation features and components. To implement internationalisation in a Spring Boot application, you need to:
Add a web dependency and use interfaces or classes to resolve or change the locale based on the request.
Configure properties and rules to specify the default locale, the supported locales, the message source
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Q24. How do you implement security in a Spring Boot application?
Answer: This type of spring boot interview questions and answers tests your knowledge of security features and components. To implement security in a Spring Boot application, you need to add a security dependency, enable and configure security, define users, roles, permissions, authentication, and authorization rules, and customise the security behaviour or handle security exceptions.
Q25. How do you implement microservices in a Spring Boot application?
Answer: Spring boot questions like these test your knowledge of microservices features and components. To implement microservices in a Spring Boot application, you need to add a cloud dependency, enable and configure microservices, design and develop your application as a collection of independent services that communicate with each other, and discover, distribute, route, handle failures or errors among your services.
Q26. How do you implement logging in a Spring Boot application?
Answer: This is one of the best Java Spring boot interview questions that test your knowledge of logging features and components. To implement logging in a Spring Boot application, you need to use the default logging framework (SLF4J and Logback) or choose another logging framework (Log4j2, JUL), configure the logging levels, patterns, formats, and appenders, using files or annotations, and use loggers or markers to generate log messages for your application.
Q27. How do you implement validation in a Spring Boot application?
Answer: This is one of the spring boot interview questions for experienced professionals that tests your knowledge of validation features and components. To implement validation in a Spring Boot application, add validation dependency. Use annotations/classes for rules on data/models. Apply validators/binders for logic/error checks. Handle validation exceptions/messages via controllers or handlers.
Q28. How do you implement scheduling in a Spring Boot application?
Answer: This is another one of the Spring Boot interview questions and answers that test your knowledge of scheduling features and components. To implement scheduling in a Spring Boot application, enable/configure scheduling with annotations/classes. Define tasks with intervals/cron expressions. Manage concurrency via thread pools/executors for scheduled methods.
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Q29. How do you implement messaging in a Spring Boot application?
Answer: This is one of the spring boot interview questions for freshers as well as experienced professionals that tests your knowledge of messaging features and components. To implement messaging in a Spring Boot application, add messaging dependency. Enable/configure messaging with annotations/classes. Define producers/consumers for systems like JMS, AMQP, and Kafka, and simplify ops with templates/channels.
Q30. How do you implement reactive programming in a Spring Boot application?
Answer: This is one of the Spring Boot interview questions for experienced individuals that test your knowledge of reactive programming features and components. To implement reactive programming in a Spring Boot application, add reactive web dependency, enable/configure reactive web, and use reactive types/operators (Mono, Flux) to handle data streams. Also, employ reactive web components (WebClient, WebFlux) for handling requests/responses.
Q31. How do you handle database transactions in a Spring Boot application?
Answer: Handling database transactions in a Spring Boot application involves using Spring's transaction management features. You can use annotations like @Transactional, and @EnableTransactionManagement, and configure transaction properties such as isolation levels, propagation behaviour, and rollback conditions. This ensures that data integrity is maintained even in case of failures.
Q32. How do you integrate Spring Boot with other Spring modules?
Answer: Integrating Spring Boot with other Spring modules is seamless due to Spring's modular design. You can utilise features like Spring Data for database access, Spring Security for authentication and authorization, and Spring Cloud for building microservices. By configuring appropriate dependencies and components, you can create a comprehensive Spring-powered application.
Q33. How do you manage application properties in a Spring Boot application?
Answer: Managing application properties in a Spring Boot application involves using various sources such as property files, environment variables, command-line arguments, and configuration classes. Spring Boot's flexible property resolution mechanism allows you to override properties in different environments or profiles, providing the necessary configuration customization.
Q34. How do you handle cross-cutting concerns in a Spring Boot application?
Answer: Handling cross-cutting concerns, such as logging, security, and caching, in a Spring Boot application can be achieved using AOP (Aspect-Oriented Programming). Spring Boot integrates seamlessly with Spring AOP, enabling you to define aspects, advice, and pointcuts to modularize and manage these concerns across the application.
Q35. How do you manage the database schema in a Spring Boot application?
Answer: This type of Spring Boot interview questions are commonly asked in interviews. Managing the database schema in a Spring Boot application is facilitated by Spring Data JPA. By defining entity classes, and repositories, and using annotations like @Entity, @Table, and @JoinColumn, you can create and evolve the database schema. Spring Boot's hibernate.ddl-auto property can automatically generate or update the schema based on your entity definitions.
Q36. How do you implement RESTful error handling in a Spring Boot application?
Answer: Implementing RESTful error handling in a Spring Boot application involves defining custom exception classes, and exception handlers, and using appropriate HTTP status codes. You can use annotations like @ExceptionHandler and ResponseEntity to return consistent error responses. This ensures that clients receive meaningful error information in a standardised format.
Q37. How do you manage database migrations in a Spring Boot application?
Answer: Managing database migrations in a Spring Boot application can be done using tools like Flyway or Liquibase. These tools allow you to version control your database schema changes and apply them in a structured manner using migration scripts. By configuring the appropriate properties, Spring Boot integrates these migration tools seamlessly.
Q38. How do you implement HATEOAS in a Spring Boot application?
Answer: Implementing HATEOAS (Hypermedia as the Engine of Application State) in a Spring Boot application involves using the Spring HATEOAS module. You can use classes like EntityModel and Link to represent resources and their relationships. By adding links to related resources, you enable clients to navigate the application's RESTful API more intuitively.
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Q39. How do you handle authentication and authorization in a microservices architecture with Spring Boot?
Answer: Handling authentication and authorization in a microservices architecture with Spring Boot can be achieved using Spring Security and OAuth2. You can centralise authentication using an Authorization Server and secure your microservices with access tokens. Spring Boot's integration with Spring Cloud Security and OAuth2 makes implementing security in a distributed system easier.
Q40. How do you implement distributed tracing in a Spring Boot microservices environment?
Answer: This is one of the important Java Spring Boot interview questions you must prepare for. Implementing distributed tracing in a Spring Boot microservices environment can be done using tools like Zipkin or Jaeger. By adding appropriate dependencies and configurations, you can trace requests as they travel through different microservices. This allows you to analyse the performance and behaviour of the entire system.
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Q41. How do you manage configuration properties for multiple microservices in Spring Boot?
Answer: Managing configuration properties for multiple microservices in Spring Boot can be achieved using Spring Cloud Config. By setting up a centralised configuration server and configuring microservices to fetch their configuration from this server, you can ensure consistency and easier management of configuration across the microservices.
Q42. How do you handle versioning and backward compatibility in RESTful APIs built with Spring Boot?
Answer: Handling versioning and backward compatibility in RESTful APIs built with Spring Boot can be achieved using different strategies such as URI versioning, custom request headers, or media type versioning. By carefully designing your API and communicating versioning changes to clients, you can ensure a smooth transition while maintaining backward compatibility.
Q43. How do you implement caching in a Spring Boot application?
Answer: Implementing caching in a Spring Boot application involves using the caching abstraction provided by Spring. You can annotate methods with @Cacheable, @CacheEvict, and @CachePut to control caching behaviour. By configuring cache managers and cache properties, you can improve performance by reducing redundant computations or database queries.
Q44. How do you handle long-running tasks in a Spring Boot application?
Answer: Handling long-running tasks in a Spring Boot application can be achieved using Spring's asynchronous features. By annotating methods with @Async and configuring thread pools, you can offload time-consuming tasks to separate threads, allowing your application to remain responsive and efficient.
Q45. How do you handle distributed transactions across multiple microservices in Spring Boot?
Answer: This is one of the common Spring Boot interview questions for experienced professionals. Handling distributed transactions across multiple microservices in Spring Boot can be challenging. You can use Spring Cloud's coordination and communication tools like Spring Cloud Sleuth and Spring Cloud Stream along with message brokers like Kafka to implement eventual consistency and manage transactions across microservices.
Q46. How do you implement real-time communication in a Spring Boot application?
Answer: Implementing real-time communication in a Spring Boot application can be done using WebSockets. By integrating Spring WebSockets and STOMP (Simple Text Oriented Messaging Protocol), you can enable bidirectional communication between clients and the server, allowing real-time updates and notifications.
Q47. How do you ensure data integrity and consistency in a distributed microservices architecture with Spring Boot?
Answer: Ensuring data integrity and consistency in a distributed microservices architecture with Spring Boot can be achieved using techniques like the Saga pattern or the Event Sourcing pattern. These patterns allow you to orchestrate and coordinate actions across microservices while maintaining data consistency and avoiding issues like distributed transactions.
Q48. How do you handle service discovery and load balancing in a Spring Boot microservices environment?
Answer: Handling service discovery and load balancing in a Spring Boot microservices environment can be done using Spring Cloud Netflix components like Eureka and Ribbon. By registering microservices with a service registry and configuring load balancers, you can enable dynamic routing and distribution of requests across instances of the same service.
Q49. How do you implement API documentation and testing for a Spring Boot RESTful API?
Answer: Implementing API documentation and testing for a Spring Boot RESTful API can be done using tools like Swagger or Springfox. By annotating your controllers with Swagger annotations and configuring Swagger UI, you can generate interactive API documentation. Additionally, tools like Postman can be used for testing API endpoints and verifying their behaviour.
Q50. How do you monitor and troubleshoot performance issues in a Spring Boot application?
Answer: This type of Spring Boot questions tests your knowledge in the interview. Monitoring and troubleshooting performance issues in a Spring Boot application can be done using tools like Spring Boot Actuator for collecting metrics and health information. Additionally, you can use monitoring solutions like Prometheus and Grafana to visualise and analyse application performance data, helping you identify and address bottlenecks and inefficiencies.
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Conclusion
Becoming skilled in Spring Boot helps developers build applications faster. It makes setting up Spring applications easier by handling configurations and dependencies. This article covered common Spring Boot interview questions for different levels of candidates. Spring Boot's tools and features let developers create efficient and secure applications while tackling modern software challenges.
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