Top 10 Critical Spring Boot Interview Questions and Answers [For Beginners & Experienced]

Nowadays, Spring boot interview questions are becoming extremely common for Java developers. Spring Boot is an open-source Java-based spring module that offers powerful features for the rapid development of deployment-ready applications. It is the most used and best java framework for the development of scalable microservices and web applications. 

If you want to become a domain expert, you have come to the right place. We have curated some the most repeatedly asked spring boot interview questions and answers to help you ace the interview.

The following article also highlights some of the most common Spring Boot interview questions for 7 years experience. 

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Basic Spring Boot Interview Questions And Answers

1. What is Spring Boot, and how is it different from Spring?

It takes the Java development with Spring to the next level and simplifies the development by removing major pain points associated with dependency, configuration, and management. The differences are listed below.

Spring

Spring Boot

It is a Java-based web application framework.

It is a module of Spring used for creating microservices.

It is quite complicated, making it difficult to use.

It is less complicated and more robust as compared to the spring framework.

It offers libraries and tools to create customized web applications.

It creates stand-alone spring application projects that can run/ execute.

It takes an un-opinionated view.

It takes an opinionated view as it can decide which defaults to deploy the configuration.

It requires XML configurations.

It does not require XML configurations.

This is one of the important Java spring boot interview questions for 10 years experience as well as beginners. 

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2. What is the need for Spring Boot?

It is one of the most commonly asked Spring Boot Interview questions, and you can answer it by pointing out significant advantages of Spring Boot. 

While Spring offers developers an ideal environment to develop large applications, the amount of configuration and its complexity makes it challenging to do so. 

Here is where Spring Boot comes to rescue. Its features like pre-built templates and auto-configuration allow developers to use existing spring functionalities with more ease, minimum effort, and maximum efficiency.

The main advantages of Spring Boot are:

• It reduces development and testing time. 
• It uses JavaConfig instead of XML.
• It provides an opinionated development approach.
• It offers starter projects or defaults for agile development.
• No separate web server is required; hence there is no need to boot up Glassfish, Tomcat, or any other server.

Read: Spring Boot Project Ideas 

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3. Can you name and briefly explain all the spring boot components/features?

This is one of the basic Spring Boot interview questions for 1-year experience candidates. 

With this question, the interviewer intends to gauge the theoretical knowledge of your concepts. If you have previous experience in the domain or worked on any Spring Boot projects, provide the answer with examples. 

The main features of Spring Boot are 

1. Starter dependency

There are many dependencies in the Spring framework, and this feature aggregates them together. Spring Boot comes packed with several starter dependencies to enhance productivity. 

Few of the Spring Boot Starters are Test Starter, Web Starter, Mail Starter, and more. For instance, if we want to use JPA and Spring for database access, we can add this starter dependency in the project-spring-boot-starter-data-jpa.

2. Auto-Configuration

This feature scans the classpath and searches the libraries/Jars in the classpath to provide the necessary configuration to design and run the application.

For example, while developing an application with Spring Boot, if there is a Thymeleaf.jar present in the classpath, it automatically can align the Thymeleaf template resolver and other settings.

3. Spring Initializer

It is a web application that simplifies the process of the project set up by creating the initial project structure and build scripts. It increases productivity by reducing development time.

4. Spring Actuator

Actuators are incredibly significant for microservices as they enable deployment-ready features like auditing, health check-up, log information, etc. for running Spring boot applications. Actuators have built-in management endpoints that are secured by default. 

This is one of the most important Spring boot microservices interview questions.

For example:

/beans– it exhibits the entire list of all Spring beans in your application.

/health— it displays application health information by monitoring the production system 

5. Spring CLI

This feature allows the developers to use Groovy for writing the Spring boot application, hence resulting in a more concise code.

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4. What is Thymeleaf in Spring Boot?

This is one of the important Java Spring Boot interview questions for all levels. 

It is a Java-based server-side template engine that offers elegant and natural templates for a web application.

5. What embedded containers are supported by Spring Boot? 

Spring Boot supports three embedded containers:

• Tomcat (used by default)
• Undertow
• Jetty

Check out: Full Stack Interview Questions & Answers

Technical Spring Boot Interview Questions And Answers

1. What do you understand by the shutdown in the actuator?

It is a management endpoint that allows for a smooth and proper shutdown of an application. It is not authorized by default, but it can be enabled by using management.endpoint.shutdown.enabled=true.

2. How and where can you define properties in Spring Boot? 

We can use the application.properties file to define features. This file gets automatically downloaded by Spring Boot and is used for application configuration.

3. Describe spring-boot-starter-parent?

It is a unique starter which adds jars to the classpath for easy Maven or Gradle dependency management.

4. What is Spring Boot dependency management?

You can explain that Spring Boot automatically manages configuration and dependencies without even stating the version for any of those dependencies.

5. Can you disable particular auto-configuration in spring boot? Explain how?

Yes, we can do that by

• Using the exclude attribute of @EnableAutoConfiguration

@Configuration

@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})

public class CustomConfiguration {}

• using the exclude attribute for @SpringBootApplication annotation

@SpringBootApplication(exclude= DataSourceAutoConfiguration.class)

public class CustomApplication {}

6. Can Spring Boot also be used to create non-web applications?

Yes, Spring Boot supports the development of both web and non-web applications. We need to remove web dependencies from the classpath and the application context to create a non-web application.

Also Read: Javascript Interview Questions

7. What are the primary dependencies of Spring Boot?

This is one of the most important Spring Boot interview questions. The following are some important dependencies:

1. Spring-boot-maven-plugin
2. Spring-boot-starter-parent
3. Spring-boot-starter-test
4. Spring-boot-starter-security
5. Spring-boot-starter-actuator
6. Spring-boot-starter-web

8. How can a Spring Boot project be generated in Eclipse?

Creating a Spring Boot project in Eclipse can be done by Spring Initializer. By visiting the official Spring website, you input details like version, choose between a Maven or Gradle project, specify the groupId and artifactId, select desired dependencies, and then initiate the project creation by clicking on “CREATE PROJECT.”

After this you can download it, extract the files, and import it into Eclipse or Spring Tool Suite (STS). Your project is then ready for use. 

9. How can a WAR file be generated in Spring Boot?

To generate a WAR file in Spring Boot, you should specify the packaging type as “war” in your pom.xml (if you are using Maven). Then do a Maven clean and install to initiate the application build. Upon completing the build, navigate to the Target folder to find the generated .war file for your application.

10. What does auto-configuration mean in Spring Boot?

AutoConfiguration is the mechanism through which Spring Boot automatically sets up all the foundational beans. It defines the predefined beans/objects of the Spring-specific module, like JPA, Spring Security, and others.

11. What are the properties of Spring Boot?

Spring Boot employs properties files to configure both its auto-configuration and application properties. Spring Boot offers multiple properties to tailor the application’s functionality. Examples of these properties are spring.profiles.active, server.port, spring.jpa.show-sql, spring.datasource.url, and more.

12. What steps can be taken to address the whitelabel error page in a Spring Boot application?

A 404 error in a Spring Boot application can be resolved through three methods:

• Implementing a Custom Error Controller: This requires making a class that follows the ErrorController interface in the Spring Framework. Modifying the getErrorPath() method allows you to define a personalized path for this type of error.
• Disabling the Whitelabel Error Page: You can deactivate the whitelabel error page effortlessly by adjusting the server.error.whitelabel.enabled property to false in the application.properties file.
• Presenting a Custom Error Page: By creating an error.html page and locating it in the src/main/resources/templates directory, the BasicErrorController in Spring Boot will automatically identify and use this file as the default error page

13. How does Spring Boot incorporate with containerization platforms such as Docker and Kubernetes?

You can package a Spring Boot application into a Docker image by creating a Dockerfile that includes necessary dependencies and settings.

Following this, the image can be constructed and launched onto containerization. Additionally, container orchestration platforms can use Spring Boot’s functionalities, such as externalized configuration and health indicators, for effective administration and scaling of the application.

14. How is Spring different from Spring Boot?

This is one of the essential Java Spring interview questions. Spring is a framework designed to offer diverse modules for constructing enterprise-level applications.

On the contrary, Spring Boot is a framework that streamlines Spring development by furnishing a pre-configured environment. This allows developers to concentrate on building the application logic. 

Spring Boot Advanced Interview Questions

The following list contains some of the advanced Spring Boot interview questions for 10 years experience. It includes both Spring Boot interview questions for 5 years experience as well as Spring Boot interview questions for 7 years experience. 

Here are some top Spring Boot interview questions for 10 years experience:

1. How can you check the environment properties in a Spring Boot application?

Ans: Spring Boot is loaded with a built-in mechanism that can be used to set the different target environments. You can set a Spring profile with the same environment name. However, before doing so, you first need to define the application environment.properties file in the resources/main directory. After you have completed these two steps, the environment file will then be automatically loaded. 

2. What do we mean by an IOC container?

Ans: Yet another very common Spring Boot interview questions for 10 years experience is the meaning of IOC container. Well, IOC container refers to the framework which is responsible for the implementation of automatic dependency injection. It serves quite a few purposes, such as injecting dependencies into a class and managing object creation and its lifeline. Whenever you need to create an object of a specified class, an IOC container is used. Furthermore, it is also responsible for injecting all the dependency objects during run time and disposing of the same at the appropriate time. Thus, you no longer need to create or manage objects manually. 

3. Can you please explain Spring Boot Dependency Management?

Ans: This one right here is perhaps one of the most important and frequently asked Spring Boot interview questions for 5 years experience. Spring Boot is responsible for managing dependencies and configuration in an automated manner. Spring Boot provides its users with a list of dependencies that it can support. You can further use this list in maven. However, while doing so, you need to at least specify the version of the dependencies. Every time you update the Spring Boot version, it automatically updates all the other dependencies. 

4. How can you create a login page in Spring Boot?

Ans: Here is another example of very frequently asked Spring Boot advanced interview questions. In order to create a simple login page in Spring Boot, you need to seek the help of Spring security. Spring security is responsible for securing all HTTP endpoints which is essential for all the users, since they have to login into the default HTTP form that is provided by Spring. Furthermore, there are also a few other steps you need to keep in mind, such as adding spring-boot-starter-security dependency in build.gradle. You will also be provided with a default username and password which you can then use for logging in. 

5. What is the procedure for creating a non-web application in Spring Boot?

Ans: Creating a non-web application or a Spring Boot standalone application is quite easy, and only involves a few steps. You need to first ensure that your application has properly implemented the CommandLineRunner interface and its Run method, essential for the running of your application. The run-method is one of the main tools of your non-web application. 

With these, we come to an end to some of the most common Spring Interview questions for 10 years experience. Hopefully, this has cleared all your doubts regarding this Java-based framework and its top features. 

6. How does Spring Boot deal with exception logging and error handling? 

This is one of the Spring Boot tricky interview questions. Spring Boot offers multiple ways to configure exception logging and error handling. By default, it provides a standard error page for unhandled exceptions. Yet, you have the flexibility to tailor error handling by using the @ControllerAdvice annotation to create custom exception handlers. This involves writing specific methods to handle different types of exceptions.

7. What is meant by the Spring Boot Annotations?

This too, is one of the Spring boot interview questions for experienced candidates. @EnableAutoConfiguration, with the help of the provided JAR dependencies, guides Spring Boot in making educated guesses about how to configure your application.

@SpringBootApplication is an annotation that marks a configuration class defining one or more @Bean methods and triggers auto-configuration and component scanning.

@ConditionalOnMissingClass is utilized within these statements to determine whether a configuration should be included based on the presence or absence of specific classes. The use of @ConditionalOnClass and @ConditionalOnMissingClass annotations is linked to conditions related to the existence of certain classes.

8. What role does the @ConfigurationProperties annotation play in Spring Boot?

The @ConfigurationProperties annotation is employed to link external configuration properties to beans managed by Spring. When you annotate a bean class with @ConfigurationProperties and define a prefix, you can associate properties with identical names to the fields or setter methods of the bean.

Spring Boot handles the automatic binding of values from configuration sources to the relevant bean properties. This annotation streamlines the process of accessing and utilizing configuration properties in your application.

9. Describe the idea of externalized logging utilizing either Logback or Log4j2.

In Spring Boot, externalized logging enables the adjustment and personalization of logging actions without altering the application code. Logback or Log4j2 may serve as the fundamental logging framework.

Usually, the setup occurs in an external configuration file like logback.xml or log4j2.xml, which can reside in the classpath or be indicated through the logging.config property. This externalized logging configuration file offers versatility in specifying log levels, appenders, formatters, and other properties related to logging.

10. Explain the function and application of the Spring Boot Admin Server for overseeing and controlling applications.

The Spring Boot Admin Server serves as a tool offering a web-based interface to centrally monitor and administer multiple Spring Boot applications. It gathers and exhibits diverse metrics, health statuses, and additional details regarding the enlisted Spring Boot applications.

Through the Admin Server, you can inspect and administer application specifics, track JVM metrics, and receive notifications for particular conditions. It streamlines the supervision and control of Spring Boot applications, especially in a production setting.

11. State the differences between Spring MVC and Spring Boot.

Spring MVC is a framework designed for constructing web applications. It uses the Model-View-Controller (MVC) architectural pattern. It incorporates functionalities for request handling, controller management, view rendering, and data flow control.

In contrast, Spring Boot is a framework built on the Spring foundation with a specific perspective, striving to streamline the establishment and setup of Spring applications.

12. What are the methods for incorporating caching into a Spring Boot application?

For this one can use Spring Framework annotations like @Cacheable and @CacheEvict. One could apply these annotations to methods to facilitate result caching. Spring Boot works with well-known caching providers like Hazelcast,  Ehcache, and Redis. This is one of the essential Spring Boot coding interview questions as it requires coding knowledge.

13. State the differences between Spring Data JPA Hibernate.

This is one of the advanced spring boot interview questions that you may be asked. Hibernate simplifies Object-Relational Mapping (ORM) tasks.  It implements the Java Persistence API (JPA). It also facilitates operations such as storing, retrieving, mapping, and updating application data between Java objects and relational databases.

Whereas, Spring Data JPA, a part of the Spring Data project, abstracts the Data Access Layer (DAL) using JPA and ORM tools like Hibernate. It streamlines the implementation of JPA repositories, aiming to improve the overall Data Access Layer.

14. Differentiate between @RestController and @Controller Annotation.

This is one of the spring boot interview questions for 7 years experience. The usual Spring @Controller annotation is like a label that says a class is supposed to be a controller. It’s a specialized form of @Component and is automatically identified through classpath scanning. The @Controller annotation is employed in conjunction with handler methods annotated with @RequestMapping.

In contrast, the @RestController annotation creates RESTful web services within the Spring Model–View–Controller (MVC) framework. The Spring @RestController maps incoming request data to designated handler methods. After the handler method produces the response body, the @RestController adapts it into an XML or JSON response.

Conclusion

Get interview ready and get your dream job with these Spring Boot interview questions and answers created by our industry experts’ team. 

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