Prepare for Your Spring Boot Interview with These Essential Questions
This comprehensive guide features 30 Spring Boot interview questions covering basic, intermediate, and advanced topics. Whether you’re a fresher, have 1-3 years of experience, or are a seasoned developer with 3-6 years, these questions will help you prepare effectively for technical interviews at companies like Amazon, Zoho, and Atlassian.
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 reduces boilerplate code and enables rapid application development.[2][3]
2. What are the key advantages of using Spring Boot?
The main advantages include auto-configuration, standalone applications, production-ready features like actuators, simplified dependency management, and embedded servers that eliminate the need for external server deployment.[1][2][3]
3. How does Spring Boot differ from the 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 XML configuration.[1][2]
4. What is Spring Boot Auto-Configuration?
Auto-configuration automatically configures Spring beans based on the dependencies present in the classpath. It uses conditional annotations to enable or disable configurations as needed.[1][2][4]
5. What is the purpose of the @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.[1][3]
6. What are Spring Boot Starters?
Spring Boot Starters are dependency descriptors that simplify adding commonly used libraries to a project. For example, spring-boot-starter-web includes all dependencies needed for web applications.[2][3]
7. What is an embedded server in Spring Boot?
Embedded servers like Tomcat, Jetty, or Undertow are included within the Spring Boot application, allowing it to run as a standalone JAR without requiring an external application server.[2][3]
8. How do you create a simple REST API in Spring Boot?
Create a class annotated with @RestController and define methods with @GetMapping, @PostMapping, etc. Spring Boot auto-configures the necessary components for handling HTTP requests.[1][3]
@RestController
public class HelloController {
@GetMapping("/hello")
public String hello() {
return "Hello, Spring Boot!";
}
}9. What is Spring Boot CLI?
Spring Boot CLI is a command-line tool that allows developers to quickly prototype and develop Spring Boot applications using Groovy scripts without needing a full Java IDE setup.[2][3]
10. What are the minimum Java version requirements for Spring Boot?
Spring Boot 3.x requires Java 17 or higher, while Spring Boot 2.x supports Java 8 and above. Always check the official documentation for the latest version requirements.[2]
Intermediate Spring Boot Interview Questions (11-20)
11. What is the difference between @Controller and @RestController?
@Controller is used for traditional MVC applications that return view names, while @RestController combines @Controller and @ResponseBody, directly writing data (usually JSON) to the HTTP response.[2][3]
12. What is Spring Boot Actuator?
Spring Boot Actuator provides production-ready features like health checks, metrics, application information, and monitoring endpoints accessible via HTTP (e.g., /actuator/health, /actuator/metrics).[1][2]
13. How do you handle exceptions globally in Spring Boot?
Use @ControllerAdvice and @ExceptionHandler annotations to create a global exception handler class that catches exceptions from all controllers and returns standardized error responses.[1]
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(Exception.class)
public ResponseEntity handleError(Exception e) {
return ResponseEntity.status(500).body("Error occurred");
}
} 14. What are Spring Profiles and how do you use them?
Spring Profiles allow environment-specific configurations (dev, test, prod). Activate profiles using spring.profiles.active property or @Profile annotation on beans.[1][5]
15. How do you externalize configuration in Spring Boot?
Use application.properties or application.yml files, environment variables, command-line arguments, or profile-specific files like application-dev.properties for different environments.[1][5]
16. What is the @Autowired annotation used for?
@Autowired enables automatic dependency injection by Spring. It can be used on fields, constructor parameters, or setter methods to inject required dependencies.[6]
17. How do you change the default port of the embedded Tomcat server?
Set the server.port property in application.properties (e.g., server.port=8081) or use the command line argument –server.port=8081 when starting the application.[6]
18. What is the difference between @GetMapping and @RequestMapping?
@GetMapping is a specialized version of @RequestMapping(method=GET) that improves code readability for GET requests. @RequestMapping supports all HTTP methods via its method attribute.[2]
19. How does Spring Boot handle dependency management?
Spring Boot uses a parent POM that provides default versions for commonly used libraries, preventing version conflicts through its dependency management mechanism.[6]
20. What is CORS and how do you handle it in Spring Boot?
CORS (Cross-Origin Resource Sharing) allows or restricts cross-domain requests. Configure it globally using WebMvcConfigurer or at controller level with @CrossOrigin annotation.[6]
Advanced Spring Boot Interview Questions (21-30)
21. Explain the internal flow of an HTTP request in Spring Boot.
Requests go through DispatcherServlet → HandlerMapping → Controller → Service → Repository → Response. The MVC pattern handles routing, business logic, and data access.[3]
22. How does Spring Boot auto-configuration work internally?
Spring Boot scans the classpath for dependencies and uses @ConditionalOnClass, @ConditionalOnMissingBean, and other conditional annotations to enable appropriate configurations.[4]
23. What are Spring Boot Actuators endpoints and how do you secure them?
Common endpoints include /health, /metrics, /info. Secure them using Spring Security by restricting access to management endpoints via management.endpoints.web.exposure.include.[1][2]
24. How do you implement data validation in Spring Boot?
Use Bean Validation annotations like @NotNull, @Size, @Email on DTO fields. Spring automatically validates request bodies and returns BindingResult errors.[4]
public class UserDTO {
@NotNull
@Size(min=2, max=30)
private String name;
}25. What is the purpose of spring-boot-starter-parent?
It provides default configurations, dependency management, and plugin versions. All Spring Boot projects typically extend this parent POM for consistent builds.[2][6]
26. How do you create custom health indicators in Spring Boot Actuator?
Implement HealthIndicator interface and return Health.up() or Health.down() based on custom checks. Spring Boot auto-registers beans implementing this interface.[1]
27. What are Spring Boot configuration properties and how do you bind them?
Create a @ConfigurationProperties class with fields matching property names (e.g., app.name binds to app.name). Enable with @EnableConfigurationProperties.[4]
@ConfigurationProperties(prefix="app")
public class AppProperties {
private String name;
// getters/setters
}28. How do you handle database connections in Spring Boot?
Use spring-boot-starter-data-jpa with application.properties settings like spring.datasource.url, username, password. Spring Boot auto-configures DataSource and EntityManager.[3]
29. What is the difference between @ComponentScan and component scanning in @SpringBootApplication?
@SpringBootApplication includes @ComponentScan by default, scanning the current package and sub-packages. @ComponentScan allows customizing base packages and include/exclude filters.[1]
30. How do you monitor application metrics in Spring Boot?
Enable actuator metrics endpoint (/actuator/metrics). Use Micrometer for custom metrics with @Timed, MeterRegistry, or Counter/Timer/Gauge registrations for JVM, HTTP, database metrics.[1][2]
Master these Spring Boot interview questions to confidently tackle technical interviews across all experience levels. Practice implementing these concepts hands-on for best results.
