Spring Interview Questions Guide: Core, Boot, MVC & More

Spring Beans and Bean Lifecycle

Spring supports several bean scopes to control how and when bean instances are created. The most common scope is singleton, where a single instance of the bean is created and shared across the entire application context. Understanding these details helps answer Spring Bean interview questions. 

The lifecycle of a Spring bean also involves various callback interfaces and annotations, such as InitializingBean, DisposableBean, @PostConstruct, and @PreDestroy, which allow you to customize initialization and destruction behavior.

Being familiar with these concepts helps you write more efficient and maintainable code, and ensures you can answer typical questions about Spring beans confidently.

Q1. What is a Spring Bean and how is it defined?
A: A Spring Bean is a Java object that is managed by the Spring IoC container. Beans are defined in configuration files (XML or Java-based), or by annotating classes with stereotypes like @Component, @Service, or @Repository.

Q2. What are the different scopes of a Spring Bean?
A: The main bean scopes are:

• Singleton (default): One shared instance per container.
• Prototype: A new instance each time the bean is requested.
• Request: One instance per HTTP request (web only).
• Session: One instance per HTTP session (web only).
• Global-session: One instance per global HTTP session (web only, for portlet applications).

Q3. Can you describe the lifecycle phases of a Spring Bean?
A: The lifecycle includes:

1. Instantiation by the container
2. Dependency injection (property population)
3. Initialization (custom logic via @PostConstruct or afterPropertiesSet())
4. Usage within the application
5. Destruction (custom logic via @PreDestroy or destroy())

Q4. How can you customize bean initialization and destruction?
A: You can use the @PostConstruct annotation or implement the InitializingBean interface for initialization logic. For destruction, use the @PreDestroy annotation or implement the DisposableBean interface. Alternatively, specify init-method and destroy-method in the bean configuration.

Q5. What is the difference between singleton and prototype beans?
A: Singleton beans have a single shared instance per Spring container, while prototype beans create a new instance each time they are requested from the container.

Quick Note: Understanding these aspects of spring beans and bean lifecycle will help you tackle both conceptual and practical questions during your interview.

Spring Application Context and BeanFactory

When working with Spring, understanding the difference between ApplicationContext and BeanFactory is essential for many technical interviews, especially for experienced developers. Both are core interfaces for accessing the Spring IoC container, but they serve different purposes. BeanFactory is the simpler, more lightweight container, mainly responsible for instantiating and wiring beans. ApplicationContext builds on BeanFactory’s capabilities by adding advanced features like internationalization, event propagation, annotation-based configuration, and application event handling. 

Choosing the right container depends on your application’s needs, but most modern Spring projects use ApplicationContext for its rich functionality and better integration with the broader Spring ecosystem.

Q1. What is BeanFactory in Spring?
A: BeanFactory is the simplest container in Spring, responsible for instantiating, configuring, and managing beans. It uses lazy initialization, meaning beans are created only when requested.

Q2. What is ApplicationContext and how is it different from BeanFactory?
A: ApplicationContext is a more advanced container that extends BeanFactory. It supports features like internationalization, event publishing, annotation-based configuration, and automatic bean post-processing. Unlike BeanFactory, ApplicationContext eagerly loads all singleton beans at startup.

Q3. When would you use BeanFactory over ApplicationContext?
A: BeanFactory is generally used in lightweight applications or environments with limited resources, where only basic bean management is needed. For most enterprise or web applications, ApplicationContext is preferred due to its additional features.

Q4. Can you give examples of ApplicationContext implementations?
A: Common implementations include ClassPathXmlApplicationContext, FileSystemXmlApplicationContext, and AnnotationConfigApplicationContext. Each is used for different configuration sources, such as XML files in the classpath or Java-based configuration.

Q5. How does ApplicationContext support internationalization?
A: ApplicationContext can load message resources from properties files, allowing you to manage messages for different locales and support multiple languages in your application.

Bottom Line: Understanding these differences and features will help you confidently discuss ApplicationContext and BeanFactory during interviews.

Spring Annotations

Spring relies heavily on annotations for configuration, wiring, and defining beans, controllers, services, and repositories. Understanding common annotations like @Autowired and @Component is essential for confidently answering annotation-related questions in interviews.

Q1. What does the @Component annotation do?
A: Marks a class as a Spring-managed component, making it eligible for component scanning and dependency injection.

Q2. Differentiate between @Component, @Service, @Repository, and @Controller.
A: All mark beans for Spring to manage, but they indicate different roles: @Component (generic), @Service (service layer), @Repository (data access), @Controller (web controller).

Q3. What is the use of @Qualifier?
A: Used with @Autowired to resolve ambiguity when multiple beans of the same type exist, specifying which bean should be injected.

Q4. How do you enable annotation-based configuration?
A: You can enable annotation-based configuration by using <context:annotation-config> or <context:component-scan> in XML, or by using @Configuration and @ComponentScan annotations in Java-based configuration classes.

Quick Recap: This approach ensures accuracy and completeness, making your interview preparation clear and helpful for readers.

Aspect-Oriented Programming (AOP) in Spring

AOP allows for the separation of cross-cutting concerns, such as logging or security, from business logic. Spring provides proxy-based AOP support.

Q1. What is Aspect-Oriented Programming (AOP)?
A: AOP is a programming paradigm that enables modularization of cross-cutting concerns like logging, security, or transactions.

Q2. What is an Aspect in Spring AOP?
A: An Aspect is a module that encapsulates a cross-cutting concern, implemented using the @Aspect annotation.

Q3. What are Advice, JoinPoint, and Pointcut?
A: Advice is the action taken at a join point (e.g., before, after, around). JoinPoint is a specific execution point in the application. Pointcut defines where advice should be applied.

Q4. What is the difference between Spring AOP and AspectJ?
A: Spring AOP is proxy-based and works at runtime, supporting method-level join points. AspectJ is more powerful, supporting compile-time and load-time weaving with broader join point coverage.

Spring Data Access (JDBC, ORM, Transactions)

Spring simplifies data access, integrates with ORM frameworks like Hibernate, and provides robust transaction management.

Q1. What is JdbcTemplate and why is it useful?
A: JdbcTemplate is a helper class that simplifies JDBC operations, reducing boilerplate code and handling exceptions.

Q2. How does Spring support ORM integration?
A: Through modules like Spring Data JPA, HibernateTemplate, and support for ORM frameworks such as Hibernate.

Q3. How is transaction management handled in Spring?
A: Using the @Transactional annotation, Spring manages transactions declaratively, supporting different propagation and isolation levels.

Q4. What is DataAccessException?
A: It’s a runtime exception provided by Spring to wrap database access errors, making error handling consistent across different data access technologies.

Spring MVC Framework

Spring MVC is a widely used web framework that helps developers build flexible and maintainable web applications. It follows the Model-View-Controller (MVC) pattern, which separates the application into three interconnected components: the model (data), the view (user interface), and the controller (business logic). 

This separation makes it easier to manage complex projects and adapt to changing requirements. Understanding Spring MVC’s architecture is especially useful for spring programming interview questions.

Q1. What is the role of DispatcherServlet in Spring MVC?
A: The DispatcherServlet acts as the front controller in Spring MVC. It receives all incoming HTTP requests, delegates them to appropriate controllers, and manages the overall request and response flow.

Q2. How does Spring MVC handle view resolution?
A: Spring MVC uses ViewResolvers, such as InternalResourceViewResolver or ThymeleafViewResolver, to map logical view names returned by controllers to actual view resources (like JSP files or HTML templates).

Q3. What is the use of @RequestMapping?
A: @RequestMapping is used to map HTTP requests to specific handler methods in controller classes, allowing you to define which URLs should trigger which business logic.

Q4. How are file uploads managed in Spring MVC?
A: File uploads are handled using the MultipartResolver interface, which processes multipart HTTP requests and extracts uploaded files for use within the application.

Quick Note: Mastering these aspects of the Spring MVC Framework will help you confidently answer web-related questions in your next interview.

Reactive Programming and Spring WebFlux

Spring WebFlux enables building non-blocking, asynchronous applications using reactive programming principles.

Q1. What is Reactive Programming and why is it important?
A: Reactive programming is a paradigm for building asynchronous, non-blocking applications that handle data streams and backpressure efficiently.

Q2. What is Spring WebFlux?
A: Spring WebFlux is a reactive web framework in Spring 5, designed for building scalable REST APIs using non-blocking I/O.

Q3. What are Publishers and Subscribers in Reactive Streams?
A: Publishers emit data, while Subscribers consume it. The API manages data flow and backpressure.

Q4. How do you handle exceptions in Spring WebFlux?
A: By implementing handlers like GlobalExceptionHandler or using WebExceptionHandler and ReactiveExceptionHandler for specific scenarios.

Key Takeaways So Far

• Reactive programming is increasingly important for modern, scalable apps.
• Spring WebFlux is the go-to for non-blocking REST APIs in Spring.
• Exception handling is similar but adapted for asynchronous flows.

Spring Boot has transformed the way developers build Java applications by providing out-of-the-box configurations, embedded servers, and a focus on rapid development. Interviewers often ask about real-world usage and practical scenarios to assess your readiness for production environments.

Q1. What is Spring Boot and how does it differ from the traditional Spring Framework?
A: Spring Boot is a framework built on top of the Spring Framework that aims to simplify application setup by offering auto-configuration, starter dependencies, and embedded servers. Unlike the traditional Spring Framework, which requires extensive manual configuration, Spring Boot enables developers to get started quickly with minimal setup.

Q2. How does Spring Boot handle embedded servers and why is this useful?
A: Spring Boot includes embedded servers like Tomcat, Jetty, or Undertow. This means you can run your application as a standalone Java process without deploying it to an external server. This approach streamlines development, testing, and deployment, making microservices and cloud-native architectures easier to implement.

Q3. What are Spring Boot Starters and why are they important?
A: Spring Boot Starters are pre-configured dependency descriptors that simplify the inclusion of commonly used libraries in your project. For example, spring-boot-starter-web bundles all dependencies needed for web development, reducing the need to specify each dependency individually.

Q4. How do you externalize configuration in Spring Boot for different environments?
A: Configuration can be externalized using property files (like application.properties or application.yml), environment variables, or command-line arguments. Profiles (e.g., application-dev.properties, application-prod.properties) allow you to define environment-specific settings and switch between them easily.

Q5. What is the purpose of Spring Boot Actuator and which endpoints are most useful in production?
A: Spring Boot Actuator provides production-ready features to help monitor and manage applications. Useful endpoints include /actuator/health (application health), /actuator/metrics (performance metrics), and /actuator/info (custom application information).

Q6. Describe a real-world scenario where you would use custom error handling in a Spring Boot REST API.
A: In a REST API, you may need to handle exceptions like validation errors or resource not found. By implementing a @ControllerAdvice with methods annotated with @ExceptionHandler, you can provide consistent error responses across your application, improving client experience and simplifying debugging.

Q7. How do you implement security in a Spring Boot application?
A: Security can be added using spring-boot-starter-security. You can configure authentication and authorization using Java configuration or properties, and customize login endpoints, password encoding, and user roles as needed.

Q8. What steps would you take to optimize a Spring Boot application for production?
A: Key steps include enabling Actuator for monitoring, using production-ready profiles, configuring logging, securing endpoints, tuning JVM and server settings, and enabling health checks. It’s also important to set up proper exception handling and to externalize all sensitive configurations.

Key Takeaways So Far

• Be ready for hands-on coding and configuration questions.
• Practice is as important as theory for interviews.
• Real code samples can set you apart from other candidates.

Many interviews include practical coding questions to assess your ability to implement Spring concepts in real projects. Practicing spring coding interview questions will help you demonstrate not only theoretical knowledge but also hands-on expertise.

Q1. How do you define a Spring bean using Java-based configuration?
Answer:

@Configuration
public class AppConfig {

    @Bean
    public MyService myService() {
        return new MyServiceImpl();
    }
}

Here, the @Configuration annotation marks the class as a configuration class, and the @Bean annotation defines a Spring bean named myService.

Q2. How do you inject dependencies using the @Autowired annotation?
Answer:

@Component
public class OrderService {

    @Autowired
    private PaymentService paymentService;

    // business methods
}

Spring automatically injects an instance of PaymentService into OrderService using field injection.

Q3. Write a simple REST controller in Spring Boot that returns a welcome message.
Answer:

@RestController
public class WelcomeController {

    @GetMapping("/welcome")
    public String welcome() {
        return "Welcome to Spring Boot!";
    }
}

This controller handles GET requests to /welcome and returns a plain text message.

Q4. How do you handle exceptions globally in a Spring Boot application?
Answer:

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(Exception.class)
    public ResponseEntity<String> handleException(Exception ex) {
        return new ResponseEntity<>("Error: " + ex.getMessage(),
                HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

The @ControllerAdvice annotation is used to define global exception handling logic for all controllers.

Q5. How can you configure a DataSource bean for JDBC in Spring?
Answer:

@Configuration
public class DataSourceConfig {

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.cj.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/mydb");
        ds.setUsername("root");
        ds.setPassword("password");
        return ds;
    }
}

This Java-based configuration sets up a DataSource bean for connecting to a MySQL database.

Quick Recap: Practicing these spring coding interview questions and answers will help you tackle practical problems and show your coding skills in any Spring interview.

Succeeding in a Spring interview requires more than just knowing the theory—it’s about clear communication, practical understanding, and confidence in applying concepts. Whether you’re preparing for spring interview questions for experienced or just starting out, here are some tips to help you perform your best.

1. Understand the Fundamentals: Make sure you have a strong grasp of core Spring concepts like IoC, Dependency Injection, bean scopes, and the differences between BeanFactory and ApplicationContext. Many spring interview questions for freshers focus on these basics.
2. Practice Coding and Real-World Scenarios: Don’t just read—write code! Practice building small applications using Spring Boot, Spring MVC, and Spring Data. Try to solve spring coding interview questions and implement features like REST APIs, security, and data access.
3. Review Annotations and Configuration: Be comfortable with commonly used annotations such as @Autowired, @Component, @Service, @Repository, and @Controller. Understand both Java-based and annotation-based configurations.
4. Stay Updated with Latest Features: Spring evolves quickly. Familiarize yourself with new modules like Spring WebFlux, and features introduced in recent versions. This is especially important for spring interview questions for experienced candidates.
5. Be Ready for Scenario-Based and Advanced Questions: Prepare for spring scenario based interview questions by thinking through real-world problems, such as handling transactions, configuring security, or troubleshooting performance issues.
6. Explain Your Thought Process: When answering, clearly explain your approach and reasoning. If you’re unsure, talk through your logic—interviewers appreciate problem-solving skills and a willingness to learn.
7. Review Common Mistakes: Avoid overusing technical jargon or giving generic answers. Make sure you can explain concepts in simple terms, and don’t hesitate to clarify a question if needed.
8. Practice Mock Interviews: Simulate real interviews with friends or online platforms. This helps reduce anxiety and improves your ability to respond to spring interview questions and answers under pressure.
9. Connect Answers to Your Experience: Whenever possible, relate your answers to projects you’ve worked on. This demonstrates practical knowledge and helps you stand out.
10. Use Official Documentation and Trusted Resources: Regularly consult the Spring documentation, reputable blogs, and sample projects to deepen your understanding and stay current.

Pro Tip: By following these tips, you’ll approach your next interview with greater confidence and be ready to tackle both basic and advanced spring interview questions effectively.

Mastering spring interview questions is an important step toward advancing your career as a Java developer. By understanding the core concepts, practicing real-world scenarios, and staying updated with the latest features in Spring, you’ll be well-prepared for any interview—whether you’re just starting out or aiming for a senior role. Keep learning, keep practicing, and approach each interview as an opportunity to showcase both your technical knowledge and problem-solving skills. With the right preparation, you’ll not only answer questions with confidence but also stand out as a valuable candidate in the competitive world of Java development.

Why It Matters?

Spring is a cornerstone of enterprise Java development. Mastering spring interview questions not only prepares you for job interviews but also builds the foundation for long-term career growth in software engineering.

Practical Advice for Learners

• Focus on both conceptual and practical aspects of Spring.
• Practice coding solutions to real-world problems.
• Review the latest Spring documentation and updates.
• Use mock interviews to build confidence.
• Relate your answers to real projects or experiences.
• Keep learning—Spring is always evolving, and so should your skills.