If you’re aiming for a Java-based development role, chances are your interview will include questions on Spring Boot. This powerful framework is widely used for building REST APIs, microservices, and enterprise-level applications. It reduces the time spent on boilerplate code and helps developers get started quickly with embedded servers and smart defaults.
To help you prepare better, we’ve created this blog with the most asked Spring Boot interview questions and their answers. These questions are selected from real interviews conducted by top tech companies. We explain each concept in simple words—from key annotations and configuration files to exception handling and actuator monitoring.
Whether you’re new to Spring Boot or want to improve your current knowledge, this resource will support your preparation journey. Use it to review core features, understand common interview patterns, and approach your next job interview with confidence.
Answer: Apache Kafka is a distributed, fault-tolerant, & scalable publish-subscribe messaging system that allows distributed app development. It is an Apache top-level project. Kafka is suitable for both online & offline message consumption.
Answer: Below are the advantages of Spring Boot:
- Spring Boot reduces the development time & boots productivity.
- It provides an opinionated auto-configuration of commonly used libraries & behaviors.
- The embedded jars in Spring Boot enable package web applications as a jar file that can run anywhere.
- The actuator module of Spring Boot provides HTTP endpoints to access application internals such as health status, inner application working, detailed metrics, etc.
Answer: The main difference between a WAR file & an embedded system is that an embedded container allows Spring Boot applications to run as a JAR directly from the command prompt without setting up any web server. However, to run a WAR file, you need to set up a web server first like Tomcat, which has a Servlet container, then you need to deploy WAR to run Spring Boot applications.
Answer: Some common Spring Boot Start POMs are spring-boot-starter-web, spring-boot-starter, & spring-boot-starter-test. You can use spring-boot-starter-web to enable Spring Model View Controller in a Spring Boot application.
Answer: Yes, you can change the port of an embedded Tomcat server through the application properties file. In this file, you need to add a property of “server.port” & assign it to any port. To assign the property to 8081, you must mention server.port=8081. After mentioning the port number, Spring Boot automatically loads the application properties file and applies the required configurations to the application.
Answer: Advice means an action taken by the aspect at a join point. There are different types of advice, including “around,” & “after,” & “before.” The main objective of aspects is to support cross-cutting concerns, like profiling, logging, caching, & transaction management.
Answer: A Proxy implies an object created after applying advice to the target object. Proxies are used to perform meta-programming operations such as altering an object’s property or intercepting an object call.
Answer: Opinionated is a design pattern that decides a way of doing things. Spring Boot is opinionated as it follows an opinionated default configuration that reduces the developer burden to configure the applications.
Answer: A String is a special immutable class which once created, cannot be changed. The string is Immutable in Java because its String objects are cached in the String pool.
Answer: Spring beans are the objects that build the foundation of all Spring applications & programs. The IOC container configures, instantiates, manages & connects Spring beans.
Answer: All three annotations (@Component, @Service, and @Repository) are part of Spring’s stereotype annotations and can be used interchangeably to mark classes for component scanning and automatic bean creation. However, they convey semantic differences:
- @Component: Generic stereotype for any Spring-managed component.
- @Service: Indicates that a class is a service layer component, often used for business logic.
- @Repository: Identifies a class as a repository, typically for data access and database interactions.
Answer: Spring Boot Starters are a set of pre-configured dependencies that help developers quickly set up specific functionality in their applications. They include both the necessary dependencies and auto-configuration classes, which make it easier to integrate certain technologies (e.g., Spring Data JPA, Spring Security, etc.) into your application. Starters simplify the process of pulling in the required dependencies and configuring them properly.
Answer: You can customize Spring Boot’s Auto-Configuration in several ways:
- Exclude specific auto-configurations using the @EnableAutoConfigurationannotation’s exclude
- Use the @ConditionalOn…annotations to control when an auto-configuration should be applied.
- Create your own auto-configuration classes using the @Configurationannotation and specify the required beans and configurations.
- Use properties in the propertiesor application.yml file to override default settings and configure specific components.
Answer: Spring Boot Auto-Configuration automatically configures beans based on the project’s classpath and the presence of certain libraries. It leverages the @ConditionalOn… annotations to conditionally enable or disable configurations. For example, if you include a database driver on the classpath, Spring Boot will automatically configure a DataSource bean unless you provide your own configuration. This feature simplifies configuration management and helps developers avoid common setup tasks.
Answer: Spring Boot is an extension of the Spring Framework that simplifies the process of building production-ready applications by providing a set of conventions, defaults, and auto-configuration. It reduces the need for complex configuration and enables developers to focus more on writing business logic. While the Spring Framework provides a comprehensive set of tools and features for building enterprise applications, Spring Boot specifically focuses on making application setup and development faster and more streamlined.
Answer: Spring Boot dependency management refers to the way Spring Boot handles the management of external libraries and dependencies required for building and running a Spring Boot application. Spring Boot is a framework that simplifies the process of developing production-ready Spring applications. Dependency management in Spring Boot involves handling the versioning and resolution of libraries that your application relies on.
Answer: Spring Boot DevTools is a module within the Spring Boot framework that serves a specific purpose in simplifying and improving the development process for Spring-based applications. Its main purpose is to enhance the developer experience by providing a set of tools and features that enable quicker and more efficient development, testing, and debugging of Spring Boot applications.
Answer: Yes, one can develop a non-web application in Spring Boot by eliminating the web-related dependencies from the classpath and altering the method through which Spring Boot generates the application context.
Answer: Choosing between Spring Boot and Spring depends on your specific needs and project requirements. Let’s go over the key differences and reasons why you might choose Spring Boot over Spring:
- Simplicity and Convention over Configuration: Spring Boot is built on top of the Spring framework but emphasizes convention over configuration. It provides a set of default configurations and sensible defaults, reducing the need for manual setup and reducing boilerplate code. This makes it easier and faster to start new projects.
- Rapid Development: Spring Boot provides a range of built-in features which speeds up development by providing common functionality out of the box, allowing you to focus on your application’s business logic.
- Microservices Support: Spring Boot is well-suited for building microservices-based applications. It includes tools for creating RESTful APIs, handling service discovery, and managing configuration for microservices architecture.
- Opinionated Defaults: Spring Boot comes with a set of opinionated defaults, making decisions for you based on best practices.
- Standalone Applications: Spring Boot allows you to create standalone applications that can be run with a simple java -jar
- Auto-Configuration: Spring Boot’s auto-configuration feature automatically configures various components based on the project’s classpath. This can significantly reduce the need to manually configure beans and settings.
- Community and Ecosystem: Spring Boot has a strong and active community. This means you can find a wealth of resources, tutorials, and community-contributed libraries that can help you accelerate your development process.
- Simplicity and Convention over Configuration: Spring Boot is built on top of the Spring framework but emphasizes convention over configuration. It provides a set of default configurations and sensible defaults, reducing the need for manual setup and reducing boilerplate code. This makes it easier and faster to start new projects.
- Rapid Development: Spring Boot provides a range of built-in features which speeds up development by providing common functionality out of the box, allowing you to focus on your application’s business logic.
- Microservices Support: Spring Boot is well-suited for building microservices-based applications. It includes tools for creating RESTful APIs, handling service discovery, and managing configuration for microservices architecture.
- Opinionated Defaults: Spring Boot comes with a set of opinionated defaults, making decisions for you based on best practices.
- Standalone Applications: Spring Boot allows you to create standalone applications that can be run with a simple java -jar
- Auto-Configuration: Spring Boot’s auto-configuration feature automatically configures various components based on the project’s classpath. This can significantly reduce the need to manually configure beans and settings.
- Community and Ecosystem: Spring Boot has a strong and active community. This means you can find a wealth of resources, tutorials, and community-contributed libraries that can help you accelerate your development process.
Answer: @ComponentScan is an annotation provided by the Spring Framework in Java that plays a significant role in the process of component scanning and auto-wiring within the Spring application context. The purpose of using @ComponentScan in class files is to instruct Spring to scan specified packages for classes that are annotated with Spring’s stereotype annotations, such as @Component, @Service, @Repository, and @Controller. These annotations are used to mark classes as Spring-managed components that should be automatically detected and registered in the Spring container during application startup.