Top 50+ Spring Boot Interview Questions and Answers (2025)
Table of Contents
1. What is Spring Framework?
Answer: Spring Framework is a Java-based framework designed to simplify enterprise application development. It provides infrastructure support for building applications and helps manage dependency injection, AOP, and transaction management.
Example: If you need a dependency injection framework to reduce boilerplate code, Spring can manage object creation and wiring.
2. What is Dependency Injection (DI) in Spring?
Answer: DI is a design pattern used by Spring to reduce tight coupling between classes by injecting dependencies (like objects or services) into a class rather than having it create those dependencies itself.
3. What are the different types of Dependency Injection in Spring?
Answer: There are three types of DI:
- Constructor Injection: Dependencies are provided through the class constructor.
@Autowired
public UserService(UserRepository userRepository) { }- Setter Injection: Dependencies are provided via setter methods.
@Autowired
public void setUserRepository(UserRepository userRepository) { }- Field Injection: Dependencies are injected directly into fields using annotations.
@Autowired
private UserRepository userRepository;4. What is the Spring Container?
Answer: The Spring Container is responsible for managing the lifecycle and dependencies of beans in a Spring application. It instantiates, configures, and manages beans based on the Spring configuration.
5. What is a Spring Bean?
Answer: A Spring Bean is a java object that the Spring IoC (Inversion of Control) container manages. These beans are instantiated, configured, and maintained by the container based on settings provided either through XML configuration or annotations.
6. What is the difference between BeanFactory and ApplicationContext?
Answer: Both are Spring container interfaces, but:
- BeanFactory is the simplest container, providing basic functionality.
- ApplicationContext extends BeanFactory and adds more features like event propagation, internationalization support, and more.
7. What are the scopes of Spring beans?
Answer: The common bean scopes in Spring are:
- Singleton: One instance for the entire application.
- Prototype: A new instance is created every time the bean is requested.
- Request: A new instance for each HTTP request.
- Session: A new instance for each HTTP session.
- Global Session: A new instance for a global HTTP session.
8. What is the role of @Component annotation in Spring?
Answer: The @Component annotation is used to mark a class as a Spring-managed bean. Spring automatically detects and registers these beans during component scanning.
9. What is the use of @Autowired annotation?
Answer: The @Autowired annotation is used to automatically wire beans in Spring. It can be applied to constructors, fields, or setter methods, and Spring will automatically inject the required dependency.
10. What is Aspect-Oriented Programming (AOP)?
Answer: AOP is a programming paradigm used by Spring to separate cross-cutting concerns (e.g., logging, transaction management) from the business logic of an application. It allows you to apply behaviors to methods or classes without modifying their code.
11. What is a Spring AOP Proxy?
Answer: A Spring AOP proxy is an object created by Spring to intercept method calls and apply additional behaviors (like logging or security checks) before or after the method execution.
12. What is the difference between @Component, @Service, @Repository, and @Controller annotations in Spring?
Answer:
- @Component: A generic stereotype annotation for any Spring-managed bean.
- @Service: A specialization of @Component, used to annotate service layer beans.
- @Repository: A specialization of @Component, used for DAO beans, typically involving database access.
- @Controller: A specialization of @Component, used to annotate controller classes in Spring MVC.
13. What is Spring Boot?
Answer: Spring Boot is an extension of the Spring Framework that simplifies the setup and development of Spring-based applications by providing defaults for configuration and reducing boilerplate code.
14. What are Spring Profiles?
Answer: Spring Profiles allow you to define beans or configurations that are specific to different environments (e.g., development, testing, production). You can activate a profile to configure Spring beans accordingly.
15. What is Spring Security?
Answer: Spring Security is a framework that provides authentication, authorization, and other security features to secure Java applications. It helps with securing both web and RESTful applications.
16. What is the Spring MVC architecture?
Answer: Spring MVC is a web framework that follows the Model-View-Controller pattern. It separates the application into three main components:
- Model: Represents the data.
- View: Represents the UI.
- Controller: Handles user input and updates the Model and View.
17. What is a DispatcherServlet in Spring MVC?
Answer: The DispatcherServlet is the front controller in Spring MVC. It intercepts all HTTP requests and forwards them to the appropriate handler methods in controllers.
18. What is a RequestMapping in Spring MVC?
Answer: @RequestMapping is an annotation used to map HTTP requests to handler methods in Spring MVC controllers. It can be used at both the class and method levels.
19. What is a Spring Boot Starter?
Answer: A Spring Boot Starter is a set of pre-configured dependencies that simplify the setup of common features (like web applications, data access, messaging, etc.) in Spring Boot applications.
20. What is the use of @SpringBootApplication annotation?
Answer: The @SpringBootApplication annotation is a convenience annotation that combines @Configuration, @EnableAutoConfiguration, and @ComponentScan. It is typically placed on the main class to launch a Spring Boot application.
21. What is the difference between @RequestMapping and @GetMapping in Spring MVC?
Answer: @RequestMapping is a general-purpose annotation that can handle all types of HTTP methods, while @GetMapping is a shortcut specifically for HTTP GET requests.
22. What is a Spring Data JPA repository?
Answer: A Spring Data JPA repository is an interface used to interact with the database in a Spring application. It extends JpaRepository or CrudRepository to provide methods for CRUD operations without needing to write implementation code.
23. What is the difference between @Transactional and @EnableTransactionManagement?
Answer:
- @Transactional: Used to define transaction boundaries on methods or classes.
- @EnableTransactionManagement: Enables Spring’s annotation-driven transaction management support.
24. What is the purpose of the @PostConstruct annotation in Spring?
Answer: The @PostConstruct annotation is used to specify a method that should be executed after the Spring bean is initialized. It’s typically used to perform initialization tasks.
25. What is the purpose of @PreDestroy annotation in Spring?
Answer: The @PreDestroy annotation is used to specify a method to be executed before a Spring bean is destroyed. It’s often used for cleanup tasks.
26. What is Spring JDBC Template?
Answer: The Spring JDBC Template is a core class in Spring that simplifies database interactions. It provides methods for executing SQL queries, updates, and stored procedures, as well as managing exceptions.
27. What is the use of @Value annotation in Spring?
Answer: The @Value annotation is used to inject values into fields from property files, environment variables, or system properties.
28. What is Spring’s @Bean annotation?
Answer: The @Bean annotation is used in Spring Java configuration to define a Spring bean explicitly. It is often used in @Configuration classes.
29. What is a Spring Event?
Answer: Spring Events are a mechanism to allow communication between different parts of an application. Components can publish events, and other components can listen for and handle those events.
30. What is the difference between @Service and @Repository in Spring?
Answer: Both @Service and @Repository are used for marking Spring beans, but:
- @Service is used for service-layer beans, typically containing business logic.
- @Repository is used for DAO (Data Access Object) beans that interact with the database.
31. What is the purpose of @Qualifier annotation in Spring?
Answer: The @Qualifier annotation is used in conjunction with @Autowired to specify which bean to inject when there are multiple candidates of the same type.
32. What is the difference between @Component and @Bean in Spring?
Answer:
- @Component: Automatically detects and registers a class as a Spring bean.
- @Bean: Used within @Configuration classes to explicitly define beans.
33. What is a Spring Boot application’s default port?
Answer: By default, a Spring Boot application runs on port 8080.
34. How can you change the default port of a Spring Boot application?
Answer: You can change the port by adding the following property in application.properties:
server.port=808135. What is the use of @PathVariable annotation in Spring MVC?
Answer: @PathVariable is used to bind a method parameter to a URI template variable in Spring MVC.
36. What is @ControllerAdvice in Spring MVC?
Answer: @ControllerAdvice is a special type of controller used to handle exceptions globally across all controllers in a Spring MVC application.
37. What is @ResponseBody in Spring MVC?
Answer: @ResponseBody indicates that the return value of a method should be written directly to the HTTP response body (e.g., for RESTful APIs).
38. What is the purpose of the @ExceptionHandler annotation in Spring?
Answer: @ExceptionHandler is used to define methods that handle exceptions thrown by controller methods in a Spring MVC application.
39. What is Spring Batch?
Answer: Spring Batch is a framework for batch processing in Java. It is used for processing large volumes of data in a reliable, transactional manner.
40. What is a Spring Boot AutoConfiguration?
Answer: AutoConfiguration is a Spring Boot feature that automatically configures your application based on the dependencies present in the classpath, so you don’t need to manually configure beans.
41. What is Spring Boot Actuator?
Answer: Spring Boot Actuator provides production-ready features, such as health checks, metrics, and application information, to help monitor and manage Spring Boot applications.
42. What is the difference between @RequestMapping and @ResponseBody?
Answer:
- @RequestMapping maps HTTP requests to controller methods.
- @ResponseBody indicates that the return value should be written to the HTTP response body.
43. What is Spring WebFlux?
Answer: Spring WebFlux is a reactive programming framework that allows building non-blocking and asynchronous web applications, useful for handling large numbers of concurrent connections.
44. What is a Spring Boot profile?
Answer: A Spring Boot profile allows you to specify different configuration settings for different environments (e.g., development, testing, production).
45. What are the key differences between Spring Boot and Spring MVC?
Answer:
- Spring Boot is used for rapid application development with minimal configuration, while Spring MVC is a more traditional framework for building web applications.
46. What is a Spring Boot starter?
Answer: A Spring Boot starter is a set of pre-configured libraries to simplify the setup of common tasks like web development, database access, and messaging.
47. What are the default configurations provided by Spring Boot?
Answer: Spring Boot provides sensible default configurations for things like embedded web servers (Tomcat), data sources, and logging.
48. How does Spring Boot support logging?
Answer: Spring Boot uses Logback by default for logging but also supports other logging frameworks like Log4j2 and java.util.logging.
49. What is the Spring Bean Lifecycle?
Answer: The Spring bean lifecycle involves the following stages:
- Bean instantiation
- Dependency injection
- Bean initialization (via @PostConstruct or InitializingBean)
- Bean destruction (via @PreDestroy or DisposableBean)
50. What is the difference between @Component and @Configuration annotations?
Answer:
- @Component: A general-purpose annotation to define Spring beans.
- @Configuration: A specialized annotation used to define classes containing Spring bean definitions (typically in Java-based configuration).
51. What is the use of @Lazy annotation in Spring?
Answer: The @Lazy annotation is used to indicate that a bean should be lazily initialized. This means that the bean will only be created when it is first requested, rather than at the startup of the application. It can help improve startup performance by deferring the creation of beans that are not immediately needed.
52. What is Spring Boot DevTools?
Answer: Spring Boot DevTools is a set of tools to improve the development experience. It includes features like automatic restarts, live reload, and enhanced logging, making it easier to develop and test Spring Boot applications.
53. What is the difference between @RequestParam and @PathVariable in Spring MVC?
Answer:
- @RequestParam: Used to bind request parameters (e.g., query parameters) to method arguments in a controller.
- @PathVariable: Used to bind URI template variables to method arguments (e.g., path variables in REST APIs).
54. What is the purpose of @EnableAutoConfiguration in Spring Boot?
Answer: @EnableAutoConfiguration tells Spring Boot to automatically configure your application based on the libraries in the classpath. It reduces the need for manual configuration of beans and helps in setting up common application features like data sources, web servers, etc.
55. What are Spring Boot Starters?
Answer: Spring Boot Starters are pre-configured sets of dependencies that simplify the process of adding common features (like web, data access, and messaging) to your application. For example, spring-boot-starter-web includes everything you need for building web applications.
56. What is Spring Cloud?
Answer: Spring Cloud is a set of tools for building cloud-native applications, specifically focusing on microservices architecture. It provides features like service discovery, configuration management, and distributed messaging.
57. What is Spring Integration?
Answer: Spring Integration is a framework for building enterprise integration solutions using messaging. It allows you to integrate various systems and applications through event-driven processing and a variety of adapters (e.g., JMS, FTP, HTTP).
58. What is the difference between @Controller and @RestController in Spring MVC?
Answer:
- @Controller: Used to define a Spring MVC controller that returns views (HTML pages).
- @RestController: A convenience annotation that combines @Controller and @ResponseBody, making it suitable for building RESTful APIs that return data, not views.
59. What is Spring Transaction Management?
Answer: Spring Transaction Management allows for consistent handling of transactions across various resources (e.g., databases, messaging systems). It provides declarative transaction management using @Transactional and programmatic transaction management.
60. What is the use of @ResponseStatus in Spring MVC?
Answer: @ResponseStatus is used to mark a method or exception class to return a specific HTTP status code. For example, you can use it to return a 404 error when an entity is not found or a 400 error for invalid input.
Read More : Top 50 Java Basic Interview Questions
Read More : Top 100 Java Medium Interview Questions
