Spring Boot is a popular Java-based framework for creating web applications. It is an open-source project that was released in 2014. Spring Boot makes it easy to create stand-alone, production-grade Spring applications that you can “just run”. It provides a number of features that make it easy to get started, such as auto-configuration, embedded servers, and starter dependencies.

Top Spring Boot interview questions and answers are provided in this blog post to assist you in passing the technical portion of the interview and becoming a successful Spring Boot Developer.

Top Spring Boot Questions and Answers

1. What is Spring Boot?

Spring Boot is an open-source Java-based framework that makes it easy to create stand-alone, production-grade Spring applications. It is designed to be easy to use and configure, and it provides a number of features that make it ideal for rapid application development.

2. Spring VS Spring boot?

•  Spring is a large framework that provides a wide range of features for building enterprise-level applications. It can be complex to learn and use, especially for beginners.
• Spring Boot is a more lightweight framework that is built on top of Spring. It provides a number of features that make it easier to develop Spring applications, such as autoconfiguration and starter dependencies. This allows developers to focus on building the application logic without having to worry about the underlying infrastructure.

3. Explain the key Features of Spring Boot.

Here are some of the key features of Spring Boot:

• Autoconfiguration: Spring Boot auto-configuration automatically configures many aspects of your application, such as the database, servlet container, and security. This can save you a lot of time and effort, and it can help you avoid making mistakes in your configuration.
• Starters: Spring Boot starters are dependency descriptors that simplify the process of adding common features to your application.
• Convention over configuration: Spring Boot follows the principle of convention over configuration. This means that Spring Boot makes assumptions about how you want your application to be configured.
• Actuator: Spring Boot Actuator is a set of production-ready features that can be used to monitor and manage your application.
• Production-ready features: Spring Boot includes a number of production-ready features, such as embedded servers, metrics, and health checks.
• Modular: Spring Boot is modular. This means that you can easily create custom applications by combining different Spring Boot modules.
• Extensible: Spring Boot is extensible. This means that you can easily add custom features to your applications.
• Community: Spring Boot has a large and active community. This means that there are many resources available to help you learn and use Spring Boot.

4. What are the Spring boot Benefits?

Spring Boot is a popular framework for building Java applications. It provides a number of benefits, including:

• Spring Boot can help you to develop applications quickly and easily.
• Production-ready: Spring Boot includes a number of production-ready features, such as embedded servers, metrics, and health checks.
• Spring Boot is designed to be scalable that you can easily add more features and users to your application without having to make major changes to your code.
• Spring Boot is modular that you can easily create custom applications by combining different Spring Boot modules.
• Spring Boot is extensible that you can easily add custom features to your applications.
• Spring Boot has a large and active community. This means that there are many resources available to help you learn and use Spring Boot.

5. What is Spring boot auto- Configuration, and How does it work?

 Spring Boot auto-configuration is a feature of Spring Boot that automatically configures many aspects of your application, such as the database, servlet container, and security. This can save you a lot of time and effort, and it can help you avoid making mistakes in your configuration.

Spring Boot auto-configuration works by scanning your classpath for Spring Boot starter dependencies. A starter dependency is a dependency that provides a set of common features for a particular type of application, such as web development or data access. When Spring Boot sees a starter dependency on your classpath, it will automatically configure the corresponding features in your application.

6. Explain the difference between a Spring Boot Starter and a Spring Boot Auto-Configuration.

A Spring Boot starter is a dependency that provides a set of common features for a particular type of application, such as web development or data access. It is a convenient way to add features to your application without having to manually configure them.

Spring Boot auto-configuration is a feature of Spring Boot that automatically configures many aspects of your application, such as the database, servlet container, and security. This can save you a lot of time and effort, and it can help you avoid making mistakes in your configuration.

7. What are the Spring Boot Annotations?

Spring Boot annotations are a set of annotations that can be used to configure and customize Spring Boot applications. These annotations are used to annotate classes, methods, and properties.

Some of the most commonly used Spring Boot annotations include:

• SpringBootApplication
• ComponentScan
• EnableAutoConfiguration
• Configuration
• Bean
• Value
• RequestMapping
• RestController

8. How do you create a Spring Boot application?

You can create a Spring Boot application by using the Spring Initializer (start.spring.io), Spring Boot CLI, or by adding Spring Boot dependencies to your existing project’s build file (e.g., Maven or Gradle).

9. How does Spring Boot handle database configuration by default?

Spring Boot provides default configurations for common databases like H2, HSQLDB, and PostgreSQL. You can customize the database connection properties in the application.properties or application.yml file.

10. How does Spring Boot simplify the configuration of data sources?

Spring Boot simplifies data source configuration by providing default settings based on the database drivers on the classpath. Developers can override these settings in the application.properties or application.yml file.

11. What are Spring Boot Starters, and why are they useful?

Spring Boot Starters are pre-configured dependencies that simplify project setup by including common libraries and configurations. They help developers get started quickly and ensure compatibility between dependencies.

12. Explain the purpose of the Spring Boot Actuator.

Spring Boot Actuator provides production-ready features such as health checks, metrics, and monitoring capabilities. It helps manage and monitor Spring Boot applications in production.

13. How can you create a RESTful web service in Spring Boot?

You can create a RESTful web service in Spring Boot by using the @RestController annotation on a class and defining endpoints using annotations like @GetMapping and @PostMapping on methods.

14. What is Spring Boot DevTools, and how does it assist developers during development?

Spring Boot DevTools is a set of tools that provides automatic application restarts, code hot swapping, and other development-related features. It improves the development experience by reducing the need for manual restarts.

15. How do you handle exceptions in a Spring Boot application?

Exceptions in Spring Boot can be handled using @ControllerAdvice to create a global exception handler or by using specific exception-handling annotations like @ExceptionHandler on methods.

16. What is the Purpose of the application.properties file in Spring Boot?

The application.properties file is used to configure application-specific properties such as database connection details, server port, and other settings.

17. How to enable HTTP/2 supports in Spring Boot?

User can enable HTTP/2 support by using server.http2.enabled configuration property.

18. Explain thymeleaf in Spring Boot.

Thymeleaf is a Java template engine that can be used to create dynamic web pages. It is a popular choice for Spring Boot applications because it is easy to use and integrates well with Spring.

19. Explain Spring CLI.

Spring CLI is used for writing in the Groovy Spring Boot application, which helps you to concise code.

20. What are embedded containers supported by Spring?

Spring Boot supports a number of embedded containers, including:

• Tomcat
• Jetty
• Undertow
• Spring Boot Actuator

21. Explain the Concept of Spring Boot Starters.

Spring Boot starters are pre-defined templates that contain a set of dependencies and configurations. They simplify the process of adding common functionality to your Spring Boot application by including all the necessary dependencies and settings.

22. What is Spring Boot Auto- Configuration, and how does it work?

Spring Boot Auto-Configuration automatically configures your application based on the dependencies and libraries you include. It scans the classpath for certain conditions and provides default configurations to simplify development.

23. How can you create a RESTful API using Spring Boot?

You can create RESTful APIs in Spring Boot by defining controller classes, mapping HTTP endpoints with annotations like @GetMapping or @PostMapping, and returning data as JSON or XML.

24. Explain the difference between Spring Boot and Spring Cloud.

 Spring Boot simplifies the development of standalone applications, while Spring Cloud focuses on building distributed systems and microservices by providing tools for service discovery, load balancing, and configuration management.

25. What is Spring Boot CommandLineRunner?

 CommandLineRunner is an interface that allows you to execute code when the Spring Boot application starts, making it useful for performing initialization tasks.

Conclusion

In this blog post, we’ve covered the Top Spring Boot interview questions and answers. Spring Boot is a powerful framework for building Java applications with ease and efficiency. By understanding these key concepts and questions, you’ll be well-prepared to tackle Spring Boot interviews and develop robust applications using this framework.