Top 25 Spring Boot Interview Questions and Answers in 2023

Spring Boot Questions and Answers

The spring boot framework is becoming increasingly popular because it makes application development quite easy. To ace your next spring boot interview, you need to demonstrate extensive knowledge of this technology. Below are the commonly asked spring boot interview questions and their answers to help you prepare adequately.

1. What Is Spring Boot?

Sprint Boot refers to a Java-based spring framework for building stand-alone microservices in Rapid Application Development. It features auto-configuration and inbuilt application server functionality, similar to tomcat and jetty. It enables us to create a self-contained application with minimum or no setup. In other words, it is a Java web framework built on microservices and available as open source. With its prebuilt code, the Spring Boot framework delivers a totally configurable and completely production-ready framework. Even though it is only an extension of the previously existing and broad spring frameworks, it has several unique characteristics that make working with the application inside the developer ecosystem easier.

2. What Are Some Common Spring Boot Features?

  • Web development

It is a spring module that is highly suited for web application development. Using embedded Tomcat, Jetty, or Undertow, one can easily develop a self-contained HTTP server.

  • Application Events and Listeners

Spring boot employs events to perform a range of activities. It enables developers to build factory files for adding listeners.

  • Admin support

Spring boot allows you to activate admin-related functionalities in an application. It is used to remotely access and administer applications.

  • SpringApplication

It’s a class that makes it easy to bootstrap a Spring application that can be launched from the main function. An application may be started simply by invoking the static run() method.

3. What Are The Benefits Of Using Spring Boot?

Spring boot helps to create self-contained Spring apps that can be launched using the java -jar command. It allows developers to embed Tomcat, Jetty, or Undertow. It provides pre-configured ‘starter’ POMs to make Maven configuration easier. Whenever possible, it configures Spring automatically.

4. What Is Meant By Auto-Configuration In Spring Boot?

Autoconfiguration is a feature, which enables library developers to configure beans in the spring context depending on various application situations, such as the availability of particular classes in the classpath, the presence of a bean, or the activation of a property. Spring Boot auto-configuration tries to set up your Spring application automatically depending on the jar dependencies you’ve supplied. A Spring-based application needs a significant amount of setup. We must configure the dispatcher servlet, view resolver, and web jars among other things while using Spring MVC.

5. What Is The Difference Between Spring Framework And Spring MVC?

The Spring Framework is the most widely used Java application development framework. The Spring Framework’s fundamental feature is dependency injection, often known as Inversion of Control (IoC). A developer may create a loosely coupled application with the Spring Framework. If the application type or attributes are well specified, it is preferable to utilize this framework. On the other hand, Spring MVC is a web application framework based on the MVC model. It has a large number of configuration files for different capabilities. It’s a framework for creating HTTP-based web applications.

6. What Approaches Can You Use To Build A Spring Boot Project Using Maven Tool?

When using the Maven software, four common approaches are used to build a spring boot project. These are Spring Maven Project, Spring Starter Project Wizard, Spring Initializr, and Spring Boot CLI. So, I would use any of these approaches.

7. Why Does Spring Boot Use Spring Starter Dependencies?

Spring Starter Dependencies are used to guarantee that your application begins with the necessary dependencies and that you can get started quickly. It might be difficult to correctly configure project dependencies as an application becomes larger. So, the Spring Boot Starter plugins aid with dependency management. The web-dependent Spring Boot Starter is an example of a spring starter dependence. This may be used to incorporate Rest Endpoints into your application. Overall, they aid in the creation of these applications by allowing a team to start from a more complicated position, resulting in fewer holes, particularly in bigger systems.

8. What Do You Understand By Spring Boot Annotations?

Annotations in Spring Boot are a type of metadata that offers information about an application. Annotations, in other words, are used to convey additional information about a program. Spring Boot Annotation isn’t included in the application being developed. It has no direct impact on the functionality of the code being annotated. Also, it does not affect the compiled program’s behavior.

9. Briefly Explain The Core Annotations Used In The Spring Framework 

  • @Required

This attribute is required for the bean setter function. It signifies that the needed property must be populated with the annotated bean at configuration time, or else an exception “BeanInitilizationException” will be produced.

  • @Autowired

The @Autowired annotation in Spring allows for annotation-based auto-wiring. It’s used to automatically wire spring beans’ setter methods, instance variables, and constructors.

  • @Configuration

This is a class-level annotation. Spring Containers uses the class marked with @Configuration as a source of bean definitions.

  • @ComponentScan

When developers wish to scan a package for beans, they use @ComponentScan. It’s used in conjunction with the @Configuration annotation. We can also select the Spring Components base packages to search for.

10. What Are The Likely Sources Of External Configuration In Spring Boot?

Here are the most common external configuration sources:

Application properties – Spring boot loads the properties by default by looking for the application properties file or its YAML file in the current directory, classpath root, or config directory.

Command-line properties – Spring boot accepts command-line inputs and transforms them into properties. The properties are then added to the collection of environmental properties.

Profile-specific properties – Properties relevant to a profile are imported from the application-{profile}.properties file or its YAML file. The {profile} placeholder consists of an active profile, and this file is located in the same directory as the non-specific property files.

11. Describe Spring Actuator And Mention Its Benefits

To debug an application and examine the logs, one must first understand what is going on in the application. So, spring Actuator is a great spring boot feature that allows a developer to examine what is going on within a running application. The Spring Actuator makes it simple to access features like bean identification, CPU consumption, and so on. In addition, the spring actuator makes it simple to get to production-ready REST points and retrieve all types of data from the web. The content negotiation strategy of Spring Security is used to secure these points.

12. What Steps Would You Follow To Create A Spring Boot Project Using Spring Initializer?

To start with, I would select the maven project as well as the dependencies that are required. After that, fill in the other relevant information, such as Group and Artifact, and then click Generate Project. Once the project has been downloaded, I would then extract it to the computer. Then, using the import option in the Spring Tool Suite IDE, I would import this project. When importing the project, I keep in mind that I must select Maven as the project type and that the source project must have the pom.xml file.

13. Explain How You Would Go About Changing The Embedded Tomcat Server Port?

The application properties file is what aids in changing the port of the embedded Tomcat server. So I make sure to add a “server. port” field to this file and assign it to whatever port I choose. If I wish to set it to port 8081, for example, I must specify server.port=8081. The application properties file will be loaded automatically by Spring Boot and the relevant configurations will be applied to the application once I indicate the port number.

14. What Are Backend Frameworks?

Backend frameworks are collections of server-side computer languages that aid in the development of a website’s backend structure. Backend frameworks offer pre-built components for building dynamic web applications. Using frameworks provides developers an advantage by removing the requirement to construct and configure everything from scratch. Because backend frameworks are developed in a variety of languages, including Python, PHP, Ruby, and Java, and have a variety of functionalities, the best backend web development framework depends significantly on the functionality required in the application.

15. Is Spring Boot A Backend Framework?

Yes. spring-boot is a backend framework that has risen to prominence in the enterprise Java community. As an open-source and lightweight backend framework, it enables Java developers to rapidly and easily create web apps. Spring boot, which was first released in 2002, makes use of the spring platform as well as third-party frameworks to help developers get up and running quickly. Backend frameworks like spring boot help developers to make application development projects easier and more pleasant. With this framework, the objective is to automate the overhead that is associated with activities of software development.

16. What Is A Bean In Spring Boot?

A bean is an object that a Spring IoC container instantiates, assembles, and generally manages. In other words, beans are the objects in spring that constitute the foundation of an application and are handled by the Spring IoC container. These are just some of the many objects in a program. Beans, as well as their interdependencies, are recorded in the container’s configuration information. One or more beans are managed by a Spring IoC container. The configuration metadata that one offers to the container, such as XML definitions, is used to produce these beans. One or more IDs are assigned to each bean. These identifiers must be distinct within the container in which the bean is housed.

17. Explain Spring Boot CLI And Its Benefits

Spring Boot CLI refers to the command-line interface that lets developers use the Groovy language to build spring-based Java applications. Because Groovy is utilized, one may develop an application using spring boot from the command line without any trouble, such as defining getter and setter methods, access modifiers, return statements, and so on. It is also quite strong and it can auto-include a lot of libraries in Groovy’s default package.

18. Why Is Spring Boot Termed As Opinionated?

Spring boot is opinionated because it chooses which configuration defaults developers can use. It also picks which dependencies to install and which packages to install. If you include the Spring Boot starter “pom” for “JPA,” for example, it will automatically configure an in-memory database, a hibernate entity manager, and a basic data source. This is an example of a default setting with a strong opinion that you may change. While some developers may find this overly opinionated, spring boot’s opinionated configuration aids developers in getting started on their projects quickly.

19. What Are The Drawbacks Of The Spring Boot Framework?

The main setback is that developers have less control when using spring boots. Many more dependencies are installed by the opinionated style since it expects that a developer will need them. Installing all of these extra dependencies, which are occasionally left unused, might make the deployment binary size very big.

Then, the Spring Boot artifact may be used to deploy Docker containers directly. This is a good way to quickly create microservices. Some developers believe, however, that the framework should not be utilized for monolithic systems because it was designed to be nimble and lightweight. Lastly, it might be difficult to upgrade your legacy Spring code. Spring Boot seeks to address such scenarios by offering a variety of tools, such as a command-line tool for transferring old code.

20. What Is Devtools In Spring Boot?

Devtools are a collection of extra development tools in spring boot that help make the application development process easier. Any project can use the spring-boot-dev tools module to offer extra development-time functionalities. A developer simply needs to add the module dependency to their build to enable dev tools support.

It offers Spring developers certain development time tools, as the name implies, to make the development process easier. Devtools gives you the ability to customize global settings that aren’t tied to any specific application. When one launches a fully packed program, the developer tools are turned off by default. When files on the classpath change, applications that utilize spring-boot-devtools will immediately restart.

21. Explain Any Three Layers In The Spring Boot Architecture

  • Presentation Layer

This is the top layer in the spring boot architecture. It is made up of Views. i.e., the application’s user interface. It is charged with handling HTTP requests and performing authentication. This layer is also responsible for transforming the parameters of JSON fields to Java Objects and vice versa. It forwards the request to the next layer after it has been authenticated. The business layer, to be precise.

  • Business Layer

All of the business logic is included in the business layer. This layer is made up of service classes. It is also responsible for authorization and validation.

  • Persistence Layer

All database storage logic is included in the persistence layer. It’s in charge of transforming business items into database rows and vice versa.

22. What Are Health Checks In Spring Boot?

The health checks simply inspect the status of an application using certain indicators. For standard components, spring boot automatically offers a health indication like a DataSource. A DataSource’s health check establishes a connection to a database and runs a basic query to inspect its status.

23. Briefly Tell Us About Spring Boot Admin And Its Purpose

Spring Boot Admin refers to a web application that allows you to manage and monitor Spring Boot apps. Each app is treated as a client and should register with the admin server. The client application registers with the admin server through HTTP or is detected by a Spring Cloud discover servers such as Eureka or Consul. Spring Actuator jars must be included in each client application. The Spring Boot Admin server polls the endpoints supplied by the Actuator jar to collect the metrics for that specific application.

24. In A Spring Boot Application, Where Can You Define Properties?

To execute the program in a different environment, properties files are used to store a large number of properties in a single file. In spring boot, properties are maintained in the file under the classpath. So I would define spring boot properties in the file called application. properties.

25. Is It Possible To Override Or Replace Embedded Tomcat Server When Using Spring Boot?

Yes, that is possible. I would use the initial dependencies to change the Embedded Tomcat with any other server. This is implemented using spring-boot-starter-jetty or as a dependency, depending on your needs. Another method of changing the server is to specify the server. port property within the resource file. For example, if I want the application to listen on port 8082, I would go ahead and indicate the server. port as 8082on the application.


You will make your interview preparation process very easy by familiarizing yourself with these questions and answers. They will help you to refresh your memory and enlighten you on areas you did not know. Also, gather some information about the employer, just in case they ask you what you know about them.

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