Spring Boot Interview Questions (Basic, JPA, Database, Exception Handling)

Preparing for backend development interviews often requires a strong understanding of modern frameworks used for building scalable web applications. One of the most widely used frameworks in the Java ecosystem is Spring Boot. It simplifies backend development by providing powerful tools for creating REST APIs, integrating databases, and building production-ready applications.

Spring Boot is built on top of the Spring framework and removes much of the complex configuration traditionally required in enterprise Java applications. Because of its simplicity and powerful features, it has become a preferred choice for building microservices, REST APIs, and enterprise backend systems.

In interviews for Java backend roles, candidates are often asked questions about Spring Boot fundamentals, REST APIs, database integration, Spring Data JPA, Hibernate, and exception handling.

This guide covers some of the most common Spring Boot interview questions along with clear explanations to help developers prepare effectively.

1. What is Spring Boot?

Spring Boot is a framework that simplifies the development of Java-based applications using the Spring ecosystem. It provides auto-configuration, embedded servers, and production-ready features that allow developers to build applications quickly.

Instead of manually configuring many components, Spring Boot automatically sets up the required configurations based on project dependencies.

2. What are the main features of Spring Boot?

Spring Boot provides several important features that simplify backend development.

These include auto-configuration, embedded web servers, starter dependencies, production-ready monitoring tools, and simplified application configuration.

These features reduce development time and make applications easier to maintain.

3. What is auto-configuration in Spring Boot?

Auto-configuration automatically configures application components based on the dependencies present in the project.

For example, if a database dependency is added, Spring Boot automatically configures the necessary database connection settings.

This feature removes the need for manual configuration.

4. What is the difference between Spring and Spring Boot?

The traditional Spring framework requires extensive configuration for setting up applications.

Spring Boot simplifies this process by providing preconfigured templates, embedded servers, and automatic dependency management.

This makes application development faster and easier.

5. What are Spring Boot starters?

Spring Boot starters are predefined dependency packages that include commonly used libraries required for specific features.

For example, the web starter includes libraries necessary for building web applications and REST APIs.

Using starters helps developers avoid manually managing multiple dependencies.

6. What is Spring Boot DevTools?

Spring Boot DevTools is a development tool that improves productivity.

It provides features such as automatic application restart, live reload, and improved development-time performance.

This allows developers to see code changes instantly without restarting the entire application manually.

7. What is Spring Data JPA?

Spring Data JPA is a module that simplifies database interactions by providing an abstraction layer over traditional database access methods.

It allows developers to perform database operations using repository interfaces instead of writing complex SQL queries.

This reduces boilerplate code and improves maintainability.

8. What is Hibernate?

Hibernate is an Object Relational Mapping (ORM) framework used to map Java objects to relational database tables.

It allows developers to interact with the database using Java objects rather than writing raw SQL queries.

Hibernate works behind the scenes when using Spring Data JPA.

9. What is an entity in Spring Boot?

An entity is a Java class that represents a table in the database.

Each field in the entity corresponds to a column in the database table.

Entities are used by Hibernate and JPA to map application objects to database records.

10. What is a repository in Spring Boot?

A repository is an interface used to perform database operations on entities.

Spring Data JPA automatically generates the implementation for repository interfaces, allowing developers to perform CRUD operations without writing SQL queries.

11. What is CRUD in Spring Boot?

CRUD stands for Create, Read, Update, and Delete.

These are the four basic operations performed on database records.

Spring Boot simplifies CRUD operations through repositories and REST controllers.

12. What is the application.properties file?

The application.properties file is used to configure application settings.

It contains configuration details such as database connections, server ports, logging settings, and other environment properties.

Spring Boot automatically reads these settings during application startup.

13. How does Spring Boot connect to a database?

Spring Boot connects to a database using configuration settings defined in the application properties file.

These settings include database URL, username, password, and driver class.

Once configured, Spring Boot automatically creates the necessary database connection.

14. What is auto table creation in Spring Boot?

Auto table creation is a feature provided by Hibernate that automatically generates database tables based on entity classes.

When the application starts, Hibernate checks the entity definitions and creates corresponding tables in the database.

This feature is useful during development.

15. What is REST in Spring Boot?

REST stands for Representational State Transfer.

Spring Boot allows developers to create REST APIs that communicate using HTTP requests and responses.

These APIs enable frontend applications or other services to interact with backend systems.

16. What is @RestController?

The @RestController annotation is used to define a class as a REST controller.

It combines the functionality of @Controller and @ResponseBody to automatically convert returned objects into JSON responses.

17. What is @RequestMapping?

@RequestMapping is used to map HTTP requests to specific controller methods.

It allows developers to define URL endpoints and the type of request method used.

18. What is @RequestBody?

@RequestBody is used to map the request body of an HTTP request to a Java object.

It is commonly used when clients send JSON data to the server.

19. What is @PathVariable?

@PathVariable extracts values from the URL path and passes them to controller methods.

It is commonly used when retrieving or modifying specific resources.

20. What is @RequestParam?

@RequestParam is used to extract query parameters from the URL.

These parameters are commonly used for filtering, searching, or pagination.

21. What is exception handling in Spring Boot?

Exception handling ensures that when errors occur in the application, they are handled properly and meaningful responses are returned to the client.

Proper exception handling prevents application crashes and improves API reliability.

22. What is global exception handling?

Global exception handling allows developers to handle exceptions across the entire application from a single location.

This ensures consistent error responses for all API endpoints.

23. What is a custom exception?

A custom exception is a user-defined exception class used to represent specific error scenarios in an application.

For example, an exception may be created to handle cases where a resource is not found.

24. What is ResponseEntity?

ResponseEntity is used to control the entire HTTP response returned by the server.

It allows developers to specify response body, HTTP status code, and headers.

This provides greater flexibility in API responses.

25. What are best practices for Spring Boot development?

Best practices include maintaining layered architecture, separating controller, service, and repository logic, implementing proper exception handling, validating input data, and using standardized API responses.

Developers should also ensure security, performance optimization, and proper logging for production-ready applications.