Top 10 Spring boot interview questions with answers

Top Spring Boot Interview Questions with Answers

 

Introduction:

Spring Boot has become one of the most popular frameworks for building Java applications due to its simplicity and ease of use. As a Spring Boot developer, you may encounter various questions during job interviews to assess your knowledge and expertise in this framework. In this blog post, we will cover some of the most frequently asked Spring Boot interview questions along with detailed answers to help you prepare and excel in your next interview.

 

1. What is Spring Boot, and what are its key features?

Answer: Spring Boot is an open-source Java framework that simplifies the development of stand-alone, production-ready Spring-based applications. Its key features include:

   - Auto-configuration: Automatically configures various components based on classpath and property settings.

   - Embedded Server: Provides an embedded Tomcat, Jetty, or Undertow server for running applications.

   - Spring Actuator: Allows monitoring and managing applications using built-in endpoints and metrics.

   - Production-Ready Defaults: Configures sensible default settings for production deployments.

 

2. How does Spring Boot differ from Spring Framework?

Answer: Spring Boot builds on top of the Spring Framework, making it easier to configure and deploy Spring-based applications. While the Spring Framework requires extensive XML configurations, Spring Boot favors convention over configuration and leverages Java-based configurations, reducing boilerplate code.

 

3. What are the different ways to create a Spring Boot application?

Answer: Spring Boot applications can be created in multiple ways:

   a) Spring Initializr: Use Spring Initializr (https://start.spring.io/) to generate a project with the required dependencies.

   b) Spring Boot CLI: Use Spring Boot Command-Line Interface to create and run Groovy scripts.

   c) Maven or Gradle: Manually configure the build tool with Spring Boot dependencies.

 

4. Explain the @SpringBootApplication annotation.

Answer: The @SpringBootApplication annotation is the core annotation used to enable Spring Boot features in a Java application. It combines three annotations:

   - @Configuration: Indicates that the class contains Spring Bean configurations.

   - @EnableAutoConfiguration: Enables Spring Boot's auto-configuration feature.

   - @ComponentScan: Scans and registers Spring components, such as beans, controllers, and services.

 

5. How does Spring Boot handle external configurations?

Answer: Spring Boot allows externalizing configurations using properties files (application.properties or application.yml) outside the application code. These properties can be overridden based on different profiles or environment variables, making it easier to manage configurations across different deployment environments.

 

6. What is Spring Boot Actuator, and what endpoints does it provide?

Answer: Spring Boot Actuator is a feature that provides production-ready monitoring and management endpoints for the application. Some common endpoints include:

   - /health: Provides application health status.

   - /info: Displays application information.

   - /metrics: Exposes various metrics about the application.

   - /env: Displays the application's environment properties.

 

7. How do you handle exceptions in Spring Boot applications?

Answer: In Spring Boot, exceptions can be handled using the @ControllerAdvice annotation combined with @ExceptionHandler methods. By annotating a class with @ControllerAdvice, you can define global exception handling logic that will apply to all controllers in your application.

 

8. How can you enable CORS (Cross-Origin Resource Sharing) in a Spring Boot application?

Answer: To enable CORS in a Spring Boot application, you can use the @CrossOrigin annotation at the controller level or configure it globally by adding a WebMvcConfigurer bean and overriding the addCorsMappings() method.

 

9. What is Spring Boot DevTools, and how does it enhance developer productivity?

Answer: Spring Boot DevTools is a set of tools that help improve developer productivity during the development phase. It includes features like automatic restarts, LiveReload for web resources, and remote debugging support, making the development process more efficient and seamless.

 

10. How can you deploy a Spring Boot application to a production environment?

Answer: Spring Boot applications can be deployed as executable JAR files or WAR files. JAR files are self-contained and can be executed directly using the `java -jar` command. WAR files can be deployed to servlet containers like Tomcat or Jetty. Additionally, Spring Boot provides options for containerized deployment using tools like Docker.

 

Conclusion:

Preparing for a Spring Boot interview requires a solid understanding of the framework's core concepts, features, and best practices. By familiarizing yourself with these commonly asked interview questions and their answers, you'll be well-equipped to showcase your knowledge and expertise during the interview process. Remember to practice implementing Spring Boot applications, explore the official documentation, and stay updated with the latest advancements in the Spring ecosystem. Good luck with your Spring Boot interviews!