Spring Interview Questions and Answers

Top 50 Spring Interview Questions and Answers 

Other Technical Interview Questions and Answers

👉 Top 50 most asked interview questions and answers with examples

1. What is the Spring Framework?

   - Answer: The Spring Framework is an open-source framework for building enterprise applications in Java. It provides comprehensive infrastructure support, making it easier to develop robust and scalable Java applications.

2. Explain Dependency Injection in Spring.

   - Answer: Dependency Injection is a design pattern in which a class receives its dependencies from an external source rather than creating them itself. In Spring, this is achieved through Inversion of Control (IoC) using techniques like constructor injection or setter injection.

3. What is the difference between Singleton and Prototype bean scopes in Spring?

   - Answer: Singleton scope means that only one instance of a bean is created per Spring container, while Prototype scope results in a new bean instance every time it is requested.

4. How does Spring MVC work?

   - Answer: Spring MVC is a module in the Spring Framework for building web applications. It follows the Model-View-Controller pattern, where the controller manages the flow of the application, the model represents the application data, and the view renders the data.

5. What is AOP (Aspect-Oriented Programming) in Spring?

   - Answer: AOP is a programming paradigm that allows modularization of cross-cutting concerns. In Spring, AOP is used to separate concerns like logging, security, and transaction management from the main business logic, promoting better code organization and maintainability.

6. Explain the concept of the Bean life cycle in Spring.

   - Answer: The Bean life cycle in Spring involves the creation, initialization, use, and destruction of a bean. It starts with bean instantiation, followed by various initialization methods, actual use of the bean, and finally destruction. Spring provides hooks for customizing this life cycle.

7. What is Spring Boot, and how does it differ from the traditional Spring Framework?

   - Answer: Spring Boot is a project within the Spring Framework that simplifies the configuration and deployment of Spring applications. It comes with defaults for application setup, reducing the need for custom configurations. Unlike the traditional Spring Framework, Spring Boot is opinionated and aims to provide a convention-over-configuration approach.

8. What is the Spring IoC container, and what are its two types?

   - Answer: The Spring IoC (Inversion of Control) container is responsible for managing the application's components. It has two types: BeanFactory and ApplicationContext. ApplicationContext is the advanced version, providing additional features like event propagation and AOP.

9. How does Spring support declarative transaction management?

   - Answer: Spring supports declarative transaction management through annotations like

@Transactional

. This allows developers to define transactional behavior at the method or class level, simplifying the handling of database transactions.

10. Explain the difference between Constructor Injection and Setter Injection in Spring.

- Answer: Constructor Injection involves injecting dependencies through the constructor of a class, while Setter Injection uses setter methods for this purpose. Constructor Injection is often preferred for mandatory dependencies, promoting immutability.

11. What is the purpose of the DispatcherServlet in Spring MVC?

- Answer: The DispatcherServlet is the front controller in Spring MVC. It receives incoming requests, processes them by invoking the appropriate controller, and manages the flow between the model and view components.

12. What is the Spring Security framework, and how does it enhance application security?

- Answer: Spring Security is a powerful and customizable authentication and access control framework for Java applications. It provides comprehensive security services, such as authentication, authorization, and protection against common security vulnerabilities.

13. How does Spring support internationalization (i18n) in applications?

- Answer: Spring supports internationalization through the use of LocaleResolver and resource bundles. It allows developers to create applications that can be easily adapted to different languages and regions.

14. Explain the purpose of the @Autowired annotation in Spring.

- Answer: The @Autowired annotation is used for automatic dependency injection in Spring. When applied to a field, method, or constructor, Spring automatically injects the required dependency at runtime, reducing the need for manual wiring.

15. What is the role of the Spring Boot Starter POMs?

- Answer: Spring Boot Starter POMs are pre-configured dependencies that help streamline the setup of various aspects in a Spring Boot application. They include common libraries and configurations for specific functionalities, making it easier to start a project with minimal setup.

16. How does Spring support method-level caching?

- Answer: Spring provides caching support through annotations such as @Cacheable and @CacheEvict. By annotating methods with these annotations, developers can cache the results of expensive method calls, improving performance.

17. What is the purpose of the Spring Data project?

- Answer: Spring Data simplifies database access in Spring applications by providing a consistent and abstracted way to interact with different data stores, including relational databases, NoSQL databases, and more.

18. Explain the difference between the @Component

, @Repository , @Service , and @Controller annotations in Spring.

- Answer: These annotations are specialization of the

@Component annotation and are used to define different types of Spring beans. @Repository is typically used for DAOs, @Service for services, and @Controller for controllers in a Spring MVC application.

19. What is the Spring Boot Actuator, and what kind of information does it provide?

- Answer: Spring Boot Actuator is a set of production-ready features provided by Spring Boot. It exposes endpoints that offer various information about the application, such as health, metrics, and environment properties.

20. How does Spring support asynchronous programming?

- Answer: Spring supports asynchronous programming through the @Async annotation. When applied to a method, it allows the method to be executed asynchronously, enhancing the performance of applications with potentially time-consuming operations.

21. What is the purpose of the @RequestMapping

annotation in Spring MVC?

- Answer: The  @RequestMapping annotation is used to map web requests to specific controller methods in Spring MVC. It allows developers to define how different HTTP requests (GET, POST, etc.) should be handled by the application.

22. Explain the concept of Spring Boot Auto-configuration.

- Answer: Spring Boot Auto-configuration automatically configures the Spring application based on the dependencies present in the classpath. It aims to reduce the need for manual configuration and boilerplate code, providing sensible defaults.

23. How does Spring support handling exceptions in a web application?

- Answer: Spring provides a centralized mechanism for handling exceptions in web applications through the use of @ControllerAdvice annotated classes. These classes can define methods to handle specific exceptions and provide a consistent error-handling strategy.

24. What is the purpose of the @Qualifier

annotation in Spring?

- Answer: The @Qualifier annotation is used to disambiguate when multiple beans of the same type are present in the Spring container. It helps specify which bean should be injected at the injection point.

25. Explain the concept of Spring Boot Profiles.

- Answer: Spring Boot Profiles allow developers to define different configurations for different environments (e.g., development, testing, production). By activating a specific profile, the application can use the corresponding configuration.

26. What is the purpose of the Spring Boot Starter Parent POM?

- Answer: The Spring Boot Starter Parent POM is the parent project object model for Spring Boot applications. It provides default configurations and dependencies, ensuring consistency across Spring Boot projects.

27. How does Spring handle circular dependencies?

- Answer: Spring handles circular dependencies by using a two-step process. First, it creates an empty instance of the bean, and then it populates the dependencies through setters or method injection. This allows Spring to resolve circular dependencies.

28. Explain the role of the @PathVariable annotation in Spring MVC.

- Answer: The @PathVariable annotation is used to extract values from the URI template and bind them to method parameters in a Spring MVC controller. It is commonly used to capture dynamic values from the URL.

29. What is the purpose of the @EnableScheduling

annotation in Spring?

- Answer: The @EnableScheduling annotation is used to enable scheduling capabilities in a Spring application. It allows the use of annotations like @Scheduled to define scheduled tasks.

30. How does Spring support method-level security?

- Answer: Spring supports method-level security through annotations such as @Secured ,@PreAuthoriz, and @PostAuthorize . These annotations allow developers to secure individual methods based on specific roles or expressions.

31. What is the purpose of the @RequestBody

annotation in Spring MVC?

- Answer: The @RequestBody annotation is used to bind the body of an HTTP request to a method parameter in a Spring MVC controller. It is commonly used to handle JSON or XML data in RESTful web services.

32. Explain the concept of Spring Boot Starters.

- Answer: Spring Boot Starters are pre-packaged dependencies that simplify the inclusion of common dependencies and configurations related to specific functionalities, such as web, data, security, etc., in a Spring Boot application.

33. What is the Spring Boot Actuator's /health

endpoint used for?

- Answer: The /health endpoint provided by Spring Boot Actuator is used to check the health of the application. It returns information about the application's health status, indicating whether it is running properly.

34. How does Spring support property file-based configurations?

- Answer: Spring supports property file-based configurations through the @PropertySource

annotation. It allows loading properties from external files, which can be accessed in the application using the @Value annotation.

35. What is the purpose of the @RequestMapping

annotation's produces attribute?

- Answer: The produces attribute in the @RequestMapping annotation specifies the media types that the controller method can produce. It helps in content negotiation, allowing the client to request specific types of response content.

36. Explain the role of the @ModelAttribute annotation in Spring MVC.

- Answer: The @ModelAttribute annotation is used to bind method parameters or method-level return values to a named model attribute. It is commonly used to prepopulate model attributes before handling a request.

37. What is Spring Boot's application.properties

file used for?

- Answer: The application.properties file in Spring Boot is used for configuring various application settings, such as database connection details, server port, logging levels, and other properties.

38. How does Spring support data validation in a web application?

- Answer: Spring supports data validation through the use of the @Valid annotation and the Validator interface. It allows developers to validate input data, and error messages can be bound to the UI through the

BindingResult object.

39. What is the purpose of the @RepositoryRestResource annotation in Spring Data REST?

- Answer: The @RepositoryRestResource

annotation is used to customize the RESTful endpoints exposed by Spring Data repositories. It allows developers to define custom paths, query parameters, and other aspects of the REST API.

40. How does Spring Boot handle external configuration properties?

- Answer: Spring Boot handles external configuration properties by allowing developers to specify property values in various external sources such as property files, environment variables, command-line arguments, and more.

41. Explain the concept of Spring Boot's @SpringBootApplication annotation.

- Answer: The @SpringBootApplication

annotation is a combination of several annotations (

@Configuration , @EnableAutoConfiguration,

@ComponentScan) and is used to bootstrap a Spring Boot application. It enables auto-configuration and component scanning.

42. What is the purpose of the @CrossOrigin

annotation in Spring MVC?

- Answer: The @CrossOrigin annotation is used to enable Cross-Origin Resource Sharing (CORS) for a specific controller or controller method in a Spring MVC application. It defines which origins are allowed to access the resources.

43. How does Spring Boot support externalized configuration?

- Answer: Spring Boot supports externalized configuration by allowing properties to be defined in external configuration files, environment variables, and command-line arguments. This flexibility makes it easy to configure applications in different environments.

44. Explain the difference between Spring Boot and Spring.

- Answer: Spring is a comprehensive framework for building enterprise Java applications, while Spring Boot is a project within the Spring ecosystem that simplifies the configuration and deployment of Spring applications by providing defaults and conventions.

45. What is the purpose of the @Scheduled annotation in Spring?

- Answer: The @Scheduled annotation is used to define scheduled tasks in a Spring application. It allows methods to be executed at fixed intervals or cron expressions, providing a way to automate recurring tasks.

46. How does Spring Boot support testing of applications?

- Answer: Spring Boot supports testing through the inclusion of the spring-boot-starter-test dependency, which provides testing utilities. It enables the use of annotations like @SpringBootTest and provides features for testing various components of a Spring Boot application.

47. What is the role of the @ConfigurationProperties

annotation in Spring Boot?

- Answer: The @ConfigurationProperties annotation is used to bind external configuration properties to Java objects in a type-safe manner. It simplifies the process of reading configuration values from properties files.

48. Explain the purpose of the Spring Boot DevTools.

- Answer: Spring Boot DevTools is a set of tools aimed at improving the development experience. It provides features like automatic application restarts, live reloading of templates, and enhanced property defaults for quicker development cycles.

49. What is the significance of the @Transactional

annotation in Spring?

- Answer: The @Transactional annotation is used to define the scope of a database transaction. When applied to a method, it ensures that the method is executed within a transaction, and if an exception occurs, the transaction is rolled back.

50. How does Spring handle circular bean dependencies, and what is a workaround if it's unavoidable?

- Answer: Spring resolves circular dependencies through a two-step process: first, it creates a proxy for one of the circular dependencies, and then it completes the injection. If unavoidable, using @Lazy or method injection can be a workaround to defer bean creation until it's actually needed.