10 Spring Boot Interview Questions Every Java Fresher Should Prepare

Most Java full stack interviews for freshers in Bangalore spend a good part of the time on Spring Boot. You do not need to know everything, but you should be able to explain these ten topics in your own words, ideally with an example from a project you built.

1. What is Spring Boot, and why use it?

Spring Boot sits on top of the Spring framework and removes most of the setup work. Auto-configuration, starter dependencies and an embedded server let you run a web app with very little code.

2. What does @SpringBootApplication do?

It combines @Configuration, @EnableAutoConfiguration and @ComponentScan, so one annotation marks the main class and starts scanning for your components.

3. Dependency injection

Instead of creating objects with new, Spring creates them (beans) and passes them where they are needed. Constructor injection is the recommended style because it makes classes easy to test.

4. @Controller vs @RestController

@RestController returns data (usually JSON) directly. @Controller is used when you return a view, such as an HTML template.

5. The three layers

Controller handles the HTTP request, Service holds the business logic, Repository talks to the database. Interviewers like it when you explain why logic should not sit in the controller.

6. Spring Data JPA and Hibernate

A repository interface such as JpaRepository<User, Long> gives you save, find and delete methods without writing SQL. Hibernate is the JPA implementation that maps your Java classes to tables.

7. application.properties

Where you set the database URL, server port and other settings. Know how profiles (dev, prod) let you keep different settings for each environment.

8. Exception handling

Use @ControllerAdvice with @ExceptionHandler to return clean error messages instead of stack traces.

9. Validation

Annotations like @NotNull, @Email and @Size on your request objects, plus @Valid in the controller, stop bad data before it reaches the database.

10. How would you secure an API?

A basic answer: Spring Security with JWT tokens, passwords stored with BCrypt, and role checks on sensitive endpoints.

How to prepare

Build one small REST API (for example, a library or an employee app) with a MySQL database and a simple React front end, then practise explaining each layer. That one project will answer most of these questions for you.

If you want a guided path with live projects and mock interviews, see the Java full stack training in Bangalore at ScholarLogic, BTM Layout.

Arjun is a counselor at ScholarLogic.