Basic Spring Boot Interview Questions (1-10)
1. What is Spring Boot?
Spring Boot is a framework that simplifies the development of Spring-based applications by providing auto-configuration, embedded servers, and starter dependencies. It eliminates the need for complex XML configurations and enables rapid application development.[1][2][3]
2. How does Spring Boot differ from Spring Framework?
Spring Boot builds on Spring Framework by adding auto-configuration, starter POMs, embedded servers, and actuators, making it easier to create production-ready applications without extensive boilerplate code.[2][3][4]
3. What are the key advantages of using Spring Boot?
The main advantages include auto-configuration, reduced boilerplate code, embedded servers, production-ready features through actuators, and simplified dependency management through starter POMs.[1][3][4]
4. What are Spring Boot Starters?
Spring Boot Starters are pre-configured dependency descriptors that simplify adding commonly used libraries like web, data JPA, security, etc., to your project. They manage transitive dependencies automatically.[3][4][5]
5. What is the purpose of @SpringBootApplication annotation?
The @SpringBootApplication annotation is a convenience annotation that combines @Configuration, @EnableAutoConfiguration, and @ComponentScan. It serves as the main entry point for Spring Boot applications.[2][4]
6. What is auto-configuration in Spring Boot?
Auto-configuration automatically configures Spring beans based on the dependencies present in the classpath. It uses conditional annotations to enable or disable configurations intelligently.[3][4][6]
7. What are the key components of Spring Boot?
The four key components are Spring Boot auto-configuration, Spring Boot CLI, Spring Boot starter POMs, and Spring Boot Actuators.[3]
8. What is Spring Boot Actuator?
Spring Boot Actuator provides production-ready features like health checks, metrics, application monitoring, and endpoints for auditing and managing applications in production.[2][3]
9. What is the difference between @Controller and @RestController?
@Controller is used for traditional web MVC controllers that return views, while @RestController combines @Controller and @ResponseBody to return data directly as JSON/XML in HTTP responses.[3][7]
10. What are Spring Boot Profiles?
Spring Boot Profiles allow environment-specific configurations like development, testing, and production. They are activated using application-{profile}.properties files.[2]
Intermediate Spring Boot Interview Questions (11-20)
11. How do you change the embedded server port in Spring Boot?
You can change the embedded Tomcat port by setting server.port in application.properties or using the command line argument --server.port=8081.[5]
12. What is the purpose of @Autowired annotation?
@Autowired enables automatic dependency injection by Spring. It injects required dependencies into beans based on type or name matching.[5][7]
13. How does Spring Boot handle dependency management?
Spring Boot provides a parent POM with curated dependency versions, preventing version conflicts and ensuring compatibility across libraries.[5][7]
14. What is the difference between @GetMapping and @RequestMapping?
@GetMapping is a specialized version of @RequestMapping for HTTP GET requests, providing better readability. @RequestMapping supports all HTTP methods via the method attribute.[3]
15. How do you create a basic REST API in Spring Boot?
Create a class annotated with @RestController, define methods with @GetMapping, @PostMapping etc., and return POJOs that get automatically converted to JSON.[7]
16. What are Spring Boot properties?
Spring Boot properties are configuration settings defined in application.properties or application.yml files that control application behavior, database connections, server settings, etc.[5]
17. How do you enable CORS in Spring Boot?
CORS can be enabled globally using @CrossOrigin at the controller level or through a WebMvcConfigurer bean for global configuration across the application.[5]
18. What is the role of @Value annotation?
@Value annotation injects values from Spring Boot properties into fields or method parameters, enabling externalized configuration.[7]
19. How does Spring Boot support externalized configuration?
Spring Boot supports externalized configuration through application.properties, YAML files, environment variables, command line arguments, and profile-specific configurations.[2]
20. What are the basic Spring Boot annotations?
Common annotations include @SpringBootApplication, @RestController, @Service, @Repository, @Autowired, @ComponentScan, and @EnableAutoConfiguration.[5][7]
Advanced Spring Boot Interview Questions (21-30)
21. Explain the internal working of a Spring Boot application.
Spring Boot starts with the main method calling SpringApplication.run(), which initializes the ApplicationContext, performs auto-configuration, scans components, and starts the embedded server.[4]
22. Describe the flow of HTTP requests in Spring Boot MVC.
HTTP requests reach the DispatcherServlet, which routes to controllers based on mappings. Controllers call services for business logic, services interact with repositories for data access, and responses return through the same path.[4]
23. How do you implement exception handling in Spring Boot?
Use @ControllerAdvice with @ExceptionHandler methods to handle exceptions globally and return standardized error responses with appropriate HTTP status codes.[2][7]
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(NullPointerException.class)
public ResponseEntity handleNullPointer(NullPointerException ex) {
return ResponseEntity.status(500).body("Null pointer exception occurred");
}
} 24. What is the Circuit Breaker pattern in Spring Boot?
Circuit Breaker prevents cascading failures in microservices by using libraries like Resilience4j. It provides fallback mechanisms when downstream services fail.[1]
25. How would you implement retry mechanisms at Paytm?
Implement Spring Retry with @Retryable annotation on service methods calling external APIs, configuring retry policies for transient failures.[1]
26. What strategies ensure fault tolerance in Salesforce microservices?
Use health checks, circuit breakers, fallback mechanisms, graceful degradation, and comprehensive logging/monitoring for fault-tolerant microservices.[1]
27. How do you perform database profiling in Spring Boot applications?
Enable Spring Boot Actuator’s database health indicators and use tools like Spring Data JPA query logging to identify slow queries and optimize database interactions.[1]
28. Explain horizontal scaling strategies for Zoho applications.
Deploy multiple Spring Boot instances behind a load balancer, use stateless design, enable session replication or external session stores, and implement caching.[1]
29. How do you implement transaction tracing at Atlassian?
Use Spring Boot Actuator’s trace endpoint combined with distributed tracing tools to follow transaction flows and identify performance bottlenecks.[1]
30. What is graceful degradation in high-load Spring Boot scenarios?
Graceful degradation prioritizes critical operations, temporarily disables non-essential features, and returns cached data during resource constraints at companies like Swiggy.[1]
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