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Top Spring Boot Interview questions you should know

Spring Boot has taken long strides in the field of application development owing to its production-ready features. Consisting of automated plugins to customize your applications, servers for automation testing, auto-configurational features with many useful annotations and starter dependencies, all of these are readily available for you.

Spring Boot is mainly written in Java. It integrates well with Spring Ecosystem like Spring JDBC, Spring ORM etc.

Spring Boot entails many state-of-the-art features and these are being frequently modified to suit the demands and requirements of developers. Indeed industries are looking for awesome developers who can build and maintain cutting edge technologies as per changing market landscape.

Spring Boot is just a product of evolving needs for reducing the time which goes into manual set up of configurations so as to focus more on creative aspects of application development.

Well, it is more to skillsets, experience and projects which you have worked upon that counts but then the idea of the interview is to gauge the personality of the interviewee, assess his problem-solving skills and decision making. Non-verbal behavior is an important factor in your assessment by the interviewer.

Hence earlier preparation of interview questions removes the unpredictability and gives one a sense of confidence to face the interview with ease. So here I have introduced some of the most important Spring Boot interview questions. To get a comprehensive idea of many more Spring Boot interview questions you can visit here.

What is Spring Boot?

Spring Boot is based on Rapid Application Development and so provides automatic configuration to applications based on the availability of dependencies in the classpath.

What is the difference between Spring and Spring Boot?

What Spring Boot does is that it automatically provides those configurations based on jar dependencies in its classpath to develop applications. So, Spring Boot is more efficient as compared to Spring.

Also, Spring works with the non-opinionated view while Spring Boot works in opinionated mode.

What is Actuator in Spring Boot ?

With the help of built-in endpoints such as HTTP & JMX, we can control Spring Boot applications.

What are the advantages of the Spring Boot Actuator ?

• With the help of the metric feature, real-time metrics such as system CPU usage, JVM memory can be analyzed.

  • Enable production-ready features to an application without having to implement them ourselves.

What is DevTools in Spring Boot?

DevTools divides classpath into two class loaders, base class loader and restart class loader.

The files which are expected to change in a project are kept in the restart classloader while tools such as JAR which rarely changes are kept in the base class loader.

Hence DevTool just restarts that particular classloader where changed files are kept.

DevTool dependency can be added in this way (for Maven) -

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-devtools</artifactId>

</dependency>

What are @EnableAutoConfiguration and @ SpringBoot Configuration annotations?

@SpringBootApplication annotation is the combination of three annotations (1) @ComponentScan (2) @Configuration (3) @EnableAutoConfiguration.

So apart from auto-configuration based on classes present in classpath, it enables Java-based configuration as well as component scanning too.

What is Spring Boot Starter?

By using Starters, development becomes much more convenient as we do not need to manually copy -paste dependencies descriptors to create required web applications.

What are some Starter dependencies?

• spring-boot-starter-test

• spring-boot-starter-security

• spring-boot-starter-web-service

• spring-boot-starter-web

What is Spring Boot dependency management?

As a result, a developer doesn’t need to worry about different versions of dependencies in the configurations as all of it is already specified and taken care of by dependency management.

What do you mean by Spring Boot supports relaxed binding?

As an example of flexible binding, we can see here

@Component

@ConfigurationProperties (prefix = “game”)

public class ConnectionSettings {

private String formatVersion ;

}

game.format-version, game.formatversion, GAME_FORMAT_VERSION

Can you change the port of Embedded Tomcat server in Spring Boot? If yes, How?

You just need to fill your desired server port by mentioning it in your “server.port”.

For example,

<Application properties>

server.port = 9000

What is YAML? What are its advantages?

YAML works well with most of the applications which require data transmission or storage.

Advantages of YAML:

• YAML makes the reading light and simple since it doesn’t involve delimiters.

• YAML makes the data understanding easy.

  • Because of the hierarchical structure, debugging is easy in YAML.

What is Thymeleaf?

It has a very clean syntax and is based on mark-up passing techniques.

It can work in both web and non-web environments and there is no hard dependency on the Servlet API.

What is the difference between @RequestMapping annotation and @GetMapping annotation?

Also, @RequestMapping can be applied on both class level and method level while @GetMapping can be only applied on the method level.

But they are similar in the sense that they support consumes.

How is Hibernate chosen as the default implementation for JPA without any configuration?

Now spring-boot-starter-data-jpa has a transitive dependency on Hibernate and JPA.

As a result, whenever Spring Boot sees Hibernate in its classpath it automatically configures Hibernate as its default implementation for JPA.

How can you create a Spring Boot project using Spring Boot Initializer?

• Choose either Maven or Gradle as a building tool for developing a project. Generally, Maven is used for building project.

• Then choose from either Java, Groovy, Kotlin as the programming language.

• Fill in project details like name, description, package name and other details.

• Then choose the type of file either from WAR or JAR.

• Click on ‘Generate’ after which the packaging of the project starts and the file gets downloaded.

  • Finally extract the downloaded file in your system and import it into your Spring Tool IDE.

What is unit testing in Spring Boot application?

While performing unit tests either on a code or method, we ensure that they are isolated from other components which interact with them.

Mockito and JUnit are some popular testing frameworks which are used for writing unit tests.

What is integration testing in Spring Boot application?

@SpringBootTest annotation is useful for writing integration tests.

Mention command to run Spring Boot application to custom port?

server.port = 8081

What is the difference between Spring MVC and Spring Boot?

• Spring Boot is designed to fasten up the process of application development by auto-configurating dependencies which are likely to be involved in application development.

  • Spring MVC is designed around the front controller pattern where the Dispatcher servlet provides a shared algorithm for request processing, while actual work is done by configurable delegate components.

With that, I would like to conclude upon the discussion to spring boot interview questions. I hope that you have got a nice idea about what are the general questions to expect in spring boot interview.

Wish you good luck for your interview :)

Knows a thing or two about interviews