Spring Boot Interview Questions

What is the Spring Framework?

Spring is a comprehensive framework for enterprise Java development that promotes modularization, testability, and scalability.

Explain Dependency Injection (DI) in Spring.

Dependency Injection is a design pattern in which a class’s dependencies are injected from the outside, typically via configuration.

What is Spring Boot?

Spring Boot is an extension of the Spring framework designed to simplify the development of production-ready applications.

Hibernate:

What is Hibernate and why is it used?

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

Explain the difference between save() and persist() in Hibernate.

Both methods are used to save an entity, but persist() is JPA-specific, while save() is Hibernate-specific.

Frontend Technologies:

What is the Document Object Model (DOM)?

The DOM is a programming interface for web documents. It represents the structure of a document as a tree of objects.

Explain the difference between var, let, and const in JavaScript.

var is function-scoped, let is block-scoped, and const is block-scoped and cannot be reassigned.

Web Technologies:

What is RESTful Web Services?

RESTful Web Services are an architectural style for designing networked applications. They use standard HTTP methods for communication.

Explain the difference between HTTP and HTTPS.

HTTPS is a secure version of HTTP that uses SSL/TLS to encrypt data transmitted between the client and server.

Database:

What is the difference between SQL and NoSQL databases?

SQL databases are relational, structured, and use SQL as the query language. NoSQL databases are non-relational and provide a flexible, schema-less data model.

Explain the ACID properties of a transaction.

ACID stands for Atomicity, Consistency, Isolation, and Durability – a set of properties that guarantee reliable processing of database transactions.

Version Control:

What is Git and how does it work?

Git is a distributed version control system. It tracks changes in files, facilitates collaboration, and allows branching and merging.

Explain the difference between Git and SVN.

Git is distributed, while SVN (Subversion) is centralized. Git allows offline work and supports branching and merging more efficiently.

Build Tools:

What is Maven and how does it differ from Ant?

Maven is a build automation and project management tool. It uses conventions over configurations, while Ant relies on XML-based build scripts.

Explain the purpose of the pom.xml file in Maven.

The pom.xml file (Project Object Model) in Maven describes the project’s configuration, dependencies, and build settings.

Testing:

What is JUnit?

JUnit is a widely-used testing framework for Java that supports the creation and execution of unit tests.

Explain the difference between unit testing and integration testing.

Unit testing focuses on testing individual units of code, while integration testing checks interactions between different components or systems.

Security:

What is Cross-Site Scripting (XSS)?

XSS is a security vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users.

How can you prevent SQL injection in Java?

Use prepared statements or parameterized queries to prevent user input from being interpreted as SQL commands.

Build and Deployment:

Explain Continuous Integration and Continuous Deployment (CI/CD).

CI/CD is a set of practices that involve automatically testing and deploying code changes frequently and consistently.

What is Docker?

Docker is a platform for developing, shipping, and running applications in containers.

REST APIs:

What is Swagger?

Swagger is a tool for designing, building, documenting, and consuming RESTful web services.

Explain the concept of HATEOAS in RESTful APIs.

HATEOAS (Hypermedia as the Engine of Application State) is an architectural constraint that aims to simplify client interaction with RESTful services.

Miscellaneous:

What is the Observer design pattern?

The Observer pattern is a behavioral design pattern where an object, known as the subject, maintains a list of its dependents, called observers, that are notified of any state changes.

Explain the concept of microservices architecture.

Microservices is an architectural style that structures an application as a collection of loosely coupled services.