10 Spring Boot Interview Questions and Answers for Java Developers

Spring Boot is one of the most widely used web and app development platforms for creating standalone applications. If you’re a web or app developer, you likely have Spring Boot in your web development toolbox. So when you’re interviewing for a web development job, be prepared to answer Spring Boot interview questions.

There’s plenty of demand for web and app developers who are proficient in Spring Boot. According to the Bureau of Labor Statistics, jobs for web developers will likely increase by 23% over the next decade.

Ready to fill one of those open web developer positions? Below, you’ll find 10 sample Spring Boot interview questions and answers that can help you ace your upcoming web developer interview.

Spring Boot Interview Questions

1. What Is Spring Boot and What Is it Used For?
2. Compare Spring Boot and Spring.
3. Describe Maven and Gradle and How They Differ.
4. Walk Me Through the Process of Creating a Spring Boot Application.
5. What Are Spring Boot Starters?
6. What Is Spring Actuator?
7. Explain How to Configure the Main Class in Spring Boot.
8. What Is Thymeleaf and How Is It Used?
9. How Would You Run a Spring Boot Application as a Java Application?
10. Describe What JPA Is in Spring Boot.

Basic Spring Boot Interview Questions

This first section will cover basic Spring Boot interview questions you might encounter during an interview for a web dev job.

Question #1: What Is Spring Boot and What Is It Used For?

Demonstrate that you have a basic understanding of what Spring Boot is and why developers use it by including these details in your answer:

• A brief description of Spring Boot.
• How it compares to other web development frameworks.
• Spring Boot’s key features.

How You Could Answer

“Spring Boot is an open-source Java-based framework developed by Pivotal Team in 2014. Developers use it to build high-quality standalone applications and microservices that are compatible with the Java Virtual Machine (JVM).

In comparison to other frameworks, Spring Boot streamlines the development of web apps and microservices through autoconfiguration. This automatically configures Spring applications based on jar dependencies.

Additionally, Spring Boot comes with built-in task support, including data binding, type conversion, exception handling, internationalization, event management, and much more.”

Question #2: Compare Spring Boot and Spring.

Spring and Spring Boot both operate on the Java framework and share some similarities.

Compare the two platforms by including the following details:

• The similarities between Spring and Spring Boot.
• How they differ.
• Their key features and functions.

How You Could Answer

“Both Spring and Spring Boot are Java-based frameworks designed for application development. However, Spring Boot is an extension of Spring and has several features and characteristics that make it different.

For example:

• Developers often use Spring Boot to create representational state transfer (REST) APIs and standalone applications. Developers typically use Spring to build enterprise Java applications and loosely coupled applications.
• Spring Boot primarily uses auto-configuration while Spring uses dependency injection.
• Spring Boot involves less boilerplate code than Spring.
• Lastly, Spring Boot works with embedded servers such as Jetty and Tomcat, while Spring requires developers to set up servers manually.”

Question #3: Describe Maven and Gradle and How They Differ.

Maven and Gradle are two Java-based build tools that are compatible with Spring Boot.

When asked Spring Boot interview questions regarding Maven and Gradle, provide the following details in your answer:

• A definition of both Maven and Gradle.
• How Maven and Gradle differ.
• The advantages and disadvantages of each.

How You Could Answer

“Maven and Gradle are both Java development tools that work with Spring Boot. Maven is an open-source build tool developed by the Apache Group. It uses Java to automate application building, run Spring Boot applications, package jar and war archives, generate build information, and more.

Gradle is a Spring Boot plugin that performs most of the same functions as Maven. However, they take different approaches to building. For example, Gradle uses a graph of task dependencies, while Maven uses fixed and linear project phases.

While Maven easily defines project metadata and dependencies, Gradle has more flexibility when it comes to creating customized builds.”

Question #4: Walk Me Through the Process of Creating a Spring Boot Application.

Now that you’ve demonstrated your knowledge of Spring Boot, it’s time to show employers your proficiency in the platform. Walk employers through the process of creating a Spring Boot application by covering the following steps:

• Creating a web controller.
• Modifying the simple main class.
• Running the application.
• Adding services.

How You Could Answer

“Creating an app with Spring Boot is simple and only takes about 15 minutes. First, I access Spring Initializer and choose Gradle or Maven to begin the process. Then, I create a web controller for a simple web application. Since Spring Initializer automatically creates a simple main class, I make any needed modifications to the class.

I then run the application by using a command. In Gradle, the command would be ./gradlew bootRun. In Maven, it would be ./mvnw spring-boot:run. Next, I test the endpoints I created for the application with a unit test. Lastly, I add any needed management services, such as security, audits, and app health.”

Question #5: What Are Spring Boot Starters?

Spring Boot works with dozens of starters to help save developers time on configuration. When asked Spring Boot interview questions regarding starters, create your answer by discussing the following:

• What Spring Boot starters are and what they do.
• Why developers use starters.
• Most commonly used starters in Spring Boot.

How You Could Answer

“In Spring Boot, starters are dependency descriptors that developers typically add to the <dependencies> section of an app’s pom.xml. Starters help reduce configuration time for developers, boost productivity, and make it easier to manage the Project Object Model.

Spring Boot has more than 50 starters that each serve a different purpose. For example, the web starter is used for building web applications containing RESTful applications. The test starter initiates the dependency to test Spring Boot applications. Developers use the data JPA starter for database access.”

Question #6: What Is Spring Actuator?

The Spring Actuator is an important tool for monitoring and managing Spring Boot web applications. Show employers that you understand how Spring Actuator works by discussing the following:

• A brief definition of Spring Actuator.
• What Spring Actuator does in Spring Boot.
• How developers utilize Spring Actuator.

How You Could Answer

“Spring Actuator is a Spring Boot sub-project that exposes the operational information of running applications by using HTTP endpoints. It allows developers to obtain health and monitoring metrics from production-ready applications. Plus, it streamlines metric gathering and traffic comprehension. Best of all, Spring Actuator is easy to use and doesn’t require any coding or configuration.”

Question #7: Explain How to Define the Main Class in Spring Boot.

Expect to answer Spring Boot interview questions regarding the main class. Formulate your answer by discussing:

• What the main class is.
• What the main class does in Spring Boot.
• How to use Maven and Gradle to define the main class.

How You Could Answer

“The main class in Spring Boot is a class that has a public static void main() method, which launches the Spring ApplicationContext. You can configure the main class in Maven or Gradle.

In Maven, the main class is defined as a start-class element in the properties section of a pom.xml file. Maven initiates the main class by executing “java -jar.” For example, the coding would look like this:

<properties>

<!-- The main class to start by executing "java -jar" -->

<start-class>application.name</start-class>

</properties>

In Gradle, the main class (mainClassName) is defined within the springBoot configuration block. It can also be defined as the mainClassName property of the bootJarGradle task. The code looks like this:

springBoot {

mainClassName = 'application.name'

}

bootJar {

mainClassName = 'application.name'

}”

Java Spring Boot Interview Questions

This next section will cover Java Spring Boot interview questions on Thymeleaf, Java Persistence API, and the steps required to run a Spring Boot application as a Java application.

Question #8: What Is Thymeleaf and How Is It Used?

As a Spring Boot developer, you’re likely familiar with the server-side Java template engine Thymeleaf. Employers may ask you to provide a description of what Thymeleaf is and how it’s used in Spring Boot. When creating your answer, discuss the following details:

• A definition of Thymeleaf.
• Which programming languages Thymeleaf supports and processes.
• How to initiate Thymeleaf in Spring Boot.

How You Could Answer

“Thymeleaf is Spring Boot’s server-side Java template engine that supports XHTML and HTML5. Developers use it for both web and standalone app projects. It’s capable of processing and creating HTML, XML, JavaScript, CSS, and plain text. To initiate Thymeleaf, developers add the following code to the pom.xml file:

<dependency>

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

<artifactId>spring-boot-starter-thymeleaf</artifactId>

</dependency>”

Question #9: How Would You Run a Spring Boot Application as a Java Application?

Some Spring Boot interview questions will gauge your ability to run applications. When asked how to run a Spring Boot application as a Java application, your answer should include the following information:

• The plugins you would need to run a Spring Boot application from.
• The required steps to run a Spring Boot application in each of the plugins.

How You Could Answer

“To run a Spring Boot application as a Java application, you would need to run it from the Spring integrated environment (IDE) plugins Eclipse or IntelliJ.

Using Eclipse, you would need to open an entry point class that contains the main method and the @SpringBootApplication annotation. Then, you would need to right-click, click on “Run As” and click on “Java Application.” You could also use the shortcut Alt-Shift-X, J.

Using IntelliJ, you would simply right-click and click on “Run ‘Application.main()’” or use the shortcut Ctrl-Shift-F10.”

Question #10: Describe What JPA Is in Spring Boot.

The Java Persistence API (JPA) is an important Spring Boot starter that developers often use to access and manage data. Include these details in your answer about JPA:

• What JPA does in Spring Boot.
• When and why developers use JPA.

How You Could Answer

“JPA stands for “Java Persistence API.” It stores and manages relational databases in Java applications. It also uses the runtime EntityManager and object-oriented Java Persistent Query Language (JPQL) to process queries on objects. Many developers prefer to use JPA for non-performance oriented complex applications because it’s easier and more efficient than hand-written mapping, Java Database Connectivity (JDBC), or Structured Query Language (SQL).”

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