Published: 07 Oct 2025 | Reading Time: 6 min
Getting into a Java full stack developer interview means facing questions spanning the entire technology stack. Unlike specialized roles testing deep expertise in one area, full stack interviews evaluate your breadth - can you discuss React component lifecycle, explain Spring Boot annotations, design database schemas, and describe deployment strategies all in the same conversation?
Interviews have become more practical in 2025. They want you to demonstrate how you integrate the front-end with the back-end, how you manage scalability in the real world, and they expect you to release the app. Basically, they are looking for the ability to create and launch whole applications, not to talk about the documentation of the frameworks.
This guide is a breakdown of 30 fundamental interview questions with their explanations for different experience levels. It not only explains the answers but also provides the reason for the question and gives the insight into what the interviewer is actually thinking. So, if you are a fresh graduate looking for your first developer job or a seasoned engineer aspiring to become a senior, knowing these questions will assist you in your strategic preparation.
A Full Stack Java Developer possesses skills in both fields of development and can work on the entire stack. Full stack development requires the knowledge of a number of tools, languages, frameworks and databases. For a Java Full Stack Developer, the interview questions typically focus on Java, web development, database systems, and cloud technologies. These interviews can include the theory and the applied problem solving. Java Full Stack Developer skills are core Java, Spring Boot, REST APIs, database integration, and modern front-end frameworks.
HTML & CSS: HTML structures the content of web pages, while CSS styles and visually formats that content.
JavaScript: Adds interactivity and dynamic behavior to web pages, enabling features like form validation, animations, and API calls.
React: A component-based architecture serves as a foundation for React - a JavaScript library renowned for its simplicity and reusability when it comes to user interface design.
React Components & JSX: Through the React framework, developers craft their application interfaces by assembling React components - small, reusable code snippets, and utilizing JSX to write HTML-like syntax inline with JavaScript.
Virtual DOM: React harnesses the power of a virtual DOM for making the necessary changes to the UI without re-rendering the slower parts, hence boosting the overall performance component.
DOM (Document Object Model): It is the representation of a web page's structure, content, styles, etc., in a way that JavaScript can modify it dynamically.
Responsive Design & Media Queries: Using responsive design concepts and media queries in CSS can help you create layouts that fit any screen size and device without any jerks or incompatibility issues.
React Developer Tools: One can use React Developer Tools, a browser extension, to effortlessly traverse, debug and improve React components along with their state.
Working on these technologies and understanding the associated concepts are vital steps in the path of building modern, responsive, and user-friendly web applications.
Node.js & Express.js: Use Node.js for server-side JavaScript; Express.js for building RESTful APIs. Implement api endpoints and use express.json middleware to parse JSON request bodies.
Spring Boot: Just utilize the embedded servers (like Tomcat) for a simple deployment. You can also create RESTful APIs and handle data with JPA.
HTTP Methods: Learn about GET, POST, PUT, DELETE, and the correspondence between these methods and CRUD operations.
JWT: Limit access to API endpoints with JWT authentication.
Thymeleaf: Utilize it as a server-side template engine for the production of interactive HTML pages in Java-based applications.
MongoDB Integration: Implement MongoDB as a NoSQL back-end that is easily accessible through Node.js or Java and use the features like aggregation and populate.
OOP Principles: Java is built on object-oriented programming (OOP) principles, including encapsulation, inheritance, polymorphism, and abstraction. Mastery of these concepts is essential for designing robust and maintainable applications.
JDK, JRE, and JVM:
MVC (Model-View-Controller): A prominent software architecture pattern in Java full stack development that divides the features into different parts for the ease of scalability and maintainability.
Spring Framework: A powerful framework for building enterprise Java applications, supporting dependency injection, MVC, and integration with databases.
Event-Driven Designs & Microservices: Modern Java applications often use event-driven architectures and microservices for scalability, flexibility, and easier maintenance.
Software Architecture: Applying strong architectural patterns ensures clean code, modular design, and the ability to scale applications as requirements grow.
Authentication & Authorization: Use strong authentication (e.g. JWT authentication or OAuth2) for definetly identification of the user, and authorization to decide which objects the user can use.
HTTPS: HTTPS should always be used to secure the confidentiality and integrity of the data exchange between client and server.
OWASP Guidelines: Adopt OWASP standards for web application security, which also includes input validation and security coding practices.
CORS (Cross-Origin Resource Sharing): Set up CORS in a way that specifies the list of authorized domains that can access your APIs. Thus, the danger of cross-site attacks is lowered.
Environment Variables: Place secrets (like API keys and database credentials) in environment variables that are secure, not in source code.
Password Hashing: When user passwords are stored in the database, they should be encrypted first, so as to be safe from hacking situations.
Journaling & Write Concern: Use database journaling and configure write concern for data durability and reliability, especially in NoSQL databases like MongoDB.
Performance Optimization:
MERN stack (MongoDB, Express.js, React, Node.js) or Java Spring are typical of full stack applications where the use of such technologies is made. These applications are built using modular design through the use of MVC (Model-View-Controller) architecture and dependency injection (Spring). Get to know how data flows, how requests and responses are handled, and how to manage state effectively. To make your application scalable, you should look into microservices architectures and event-driven designs. Measure the efficiency of your application all through the stack and adhere to the recommended software architecture practices.
CI/CD Pipelines: Create continuous integration and continuous delivery pipelines (with the help of tools such as GitHub Actions or Jenkins) to automate your app building, testing, and releasing.
Docker: Use Docker to containerize your applications so that your development, testing, and production environments are all consistent.
Build Tools & Dependency Management: Apply build tools like Maven or Gradle for Java projects to automate the builds and manage the dependencies.
Cloud Services & Hosting Environments: Install your applications on cloud services (AWS, Azure, Google Cloud) or on managed hosting environments for scalability and reliability.
Deployment Automation: Automate deployment processes to reduce manual intervention and speed up release cycles.
GitHub Profile & Team Collaboration Features: Maintain a strong GitHub profile to showcase your projects and facilitate team collaboration with pull requests, code reviews, and clear workflows.
Modular Architecture: Design your app with a modular architecture to be able to keep it under control and expand it with less effort.
Real-Time Updates: Add functionalities such as WebSockets or Redis to your application so that it can have real-time updates and become more interactive.
Scalability Issues: Take the issue of scalability off your back by making your code efficient, utilizing cloud resources and keeping track of your system performance to be able to manage higher loads in a smooth manner.
By following these practices and utilizing these tools, you can efficiently build, deploy, and maintain robust, scalable full stack applications in real-world scenarios.
Git & GitHub: Use Git for version control—understand the basics: clone, add, commit, push, and pull. Maintain your codebase in a Git repository and follow a clear Git workflow.
Branching Strategy & Merge Conflict Resolution: Use feature branches, follow a branching strategy, and resolve merge conflicts efficiently. Write meaningful commit messages to track changes.
CI/CD Pipelines: Automate the construction, testing, and deployment processes through CI/CD pipelines that utilize GitHub Actions or Jenkins as your tooling.
Docker: Wrap your applications in containers through Docker so that the deployment is always the same regardless of the environment.
Build & Dependency Management Tools: Utilise tools such as Maven, Gradle, and Flyway for building, dependency management, and database migrations.
Best Practices: Maintain code quality, automate repetitive tasks, and collaborate effectively for scalable, reliable full stack development.
Quick Note: Java full stack doesn't mean equal expertise everywhere. Most developers lean toward backend (Java/Spring Boot) or frontend (React/Angular) while maintaining working knowledge across the complete stack.
The following questions represent typical Java Full Stack Developer interview queries that entry-level candidates should expect during job interviews:
A web developer who specializes in Java Full Stack Development handles both user interface design and backend programming for web applications. The front-end development relies on HTML CSS JavaScript alongside Angular or React frameworks. For back-end development, we use Java with frameworks like Spring Boot to build RESTful APIs, manage databases, and handle business logic.
MVC stands for Model-View-Controller. It is an architectural pattern used to separate an application into three main components:
The key differences between Java and Python are listed below:
| Java | Python |
|---|---|
| Statically typed (variable types must be declared). | Dynamically typed (variable types are inferred). |
| Faster execution due to compilation and JVM optimization. | Slower execution as it is an interpreted language. |
| More verbose, and uses curly braces and semicolons. | Simpler, and resembles human language, with no semicolons. |
A Java servlet functions as a class which manages HTTP requests to produce dynamic content. Web servers use this technology to expand their features by executing form submissions and database queries.
Two programmers work in partnership using pair programming to develop code together in real-time. The driver takes responsibility for creating the code while the navigator checks the code to provide feedback and maintain its quality. The development methodology promotes team collaboration together with code improvement and mutual knowledge exchange.
CORS stands for Cross-Origin Resource Sharing. Web browsers utilize CORS as a security protocol that enables them to access resources from different domains than the page origin. Through permission management CORS defines which origins are allowed to access resources which protects against harmful cross-site attacks.
A callback function in JavaScript is a function that is passed as an argument to another function and is executed later, once a specific event or operation is completed. Callbacks are typically used for handling asynchronous operations, like network requests or timers, but they can also be used for other purposes, such as iterating over data or event handling.
Example:
function greeting(name) {
alert("Hello, " + name);
}
function processUserInput(callback) {
var name = prompt("Please enter your name.");
callback(name); // The callback function is executed here
}
processUserInput(greeting); // greeting is passed as a callback
Long polling represents a web development method which enables web servers to deliver updates to clients without the need for continuous client requests. The client-server connection remains active while the server delivers data only when it becomes available.
Applications which need immediate information updates like chat programs and collaborative editing tools benefit from this method. This method of server communication operates efficiently because it lowers the number of unnecessary client requests and decreases the amount of work needed by the server.
CSS selectors can be:
The DOM is a programming interface for web documents. It represents the structure of an HTML or XML document as a tree of nodes, each node representing a part of the document (elements, attributes, text, etc.).
JavaScript is a lightweight, interpreted programming language used for client-side scripting in web pages, whereas Java is a statically typed, compiled programming language used for building standalone applications and server-side applications.
AJAX (Asynchronous JavaScript and XML) allows web pages to load content asynchronously without reloading the entire page. It uses the XMLHttpRequest object or the fetch API to send HTTP requests and update parts of the page dynamically.
Here is the comparison between HTML and HTML5:
| HTML | HTML5 |
|---|---|
| It does not have native support for audio and video. Requires third-party plugins. | It contains native support for audio and video elements ( |
| Limited form elements. Lacks advanced input types (e.g., date, email). | New form elements and input types like , . |
| Limited use of semantic tags. Relies on generic and . |
Introduces semantic tags like , , , , and . |
A session in web applications refers to the way entities are interacted with and engaged during a shared period in time spanning multiple clicks or actions. In essence, a web application session forms a unique window of interaction with the application, where a user may be identified through unique credentials which may be collected and analyzed for user experience via analytics and recommendation systems. Sessions are a necessity for user verification, monitoring e-commerce activities such as add to cart or track items, and recording temporary settings selected by the user.
Hibernate is an open-source Object-Relational Mapping (ORM) framework for Java. It simplifies database interactions by mapping Java objects to relational database tables and vice versa. Hibernate provides a way to interact with a database using high-level object-oriented code, rather than writing raw SQL queries. This results in easier maintenance, better portability, and a more flexible system.
Dependency Injection (DI) in Spring is a design pattern where Spring Framework automatically provides dependencies (objects or services) to a class, promoting loose coupling and easier testing by injecting them via constructors, setters, or fields.
Here is the comparison of GET and POST:
| GET | POST |
|---|---|
| The purpose is to retrieve data from the server. | The purpose is to send data to the server (e.g., form submission). |
| GET is idempotent (the same request returns the same result). | POST is not idempotent (submitting the same data multiple times may cause changes). |
| Data is visible in the URL. | Data is hidden in the request body. |
Experienced Java Full Stack Developer interview questions often cover a broad range of topics, assessing deep understanding and practical application across various layers of development.
Here is the comparison of Spring MVC and Spring Boot:
| Spring MVC | Spring Boot |
|---|---|
| Requires extensive configuration. | Pre-configured, minimal setup required. |
| Used for manual setup for dependencies. | Used for auto-configuration for faster setup. |
| Slower development due to more setup. | Faster development due to built-in features. |
| More complex and customizable. | Simpler and easier to use. |
The @RestController annotation in Spring is used to define a controller that handles HTTP requests and returns responses directly to the client in the form of JSON or XML. It is a convenience annotation that combines @Controller and @ResponseBody to simplify RESTful web service development.
Benefits:
RESTful Web Services are web services based on REST (Representational State Transfer) principles, which use HTTP methods (GET, POST, PUT, DELETE) for communication between client and server. They are stateless, scalable, and cacheable, making them ideal for web and mobile applications.
WebSockets function as a protocol which establishes continuous bidirectional interactions between client devices and servers. WebSockets show uninterrupted real-time communication which surpasses standard HTTP request capabilities. Live data update applications such as chat platforms and notification systems find WebSockets perfect for maintaining real-time information delivery.
Spring utilizes the @Transactional annotation to establish transaction borders. Spring validates execution of database operations within a single transaction for methods using the annotation which commits or rolls back operations based on method success or failure.
| Session-based Authentication | Token-based Authentication |
|---|---|
| Stored on the server | Stored on the client (usually in local storage or cookies) |
| Less scalable, as the server holds sessions | Highly scalable, as tokens are stateless |
| Slower as session data is looked up on the server | Faster, as the client manages the token |
Docker is a containerization platform that allows developers to package applications and their dependencies into containers. This makes it easier to deploy and run applications consistently across different environments. Docker enhances the development, testing, and deployment processes in full-stack development by providing an isolated, reproducible environment.
Benefits:
Spring Boot is a framework built on top of the Spring framework. It simplifies the development of production-ready applications by providing defaults for configurations, embedded servers (like Tomcat, and Jetty), and automatic dependency management. It reduces the need for complex configurations and helps in rapid development. Spring Boot allows you to create stand-alone applications that can run directly without an external servlet container.
JUnit and TestNG are popular testing frameworks in Java. Unit tests are written to test individual units of code, such as methods or classes. These tests check whether the code behaves as expected. You can use annotations like @Test in JUnit and @Test in TestNG to define test methods and assertions to verify results.
A Promise represents the eventual completion (or failure) of an asynchronous operation. It has three states:
To prove yourself during your Java Full Stack Developer job interview the following advice will prove helpful:
Java full stack developer interviews assess breadth across multiple technologies while testing depth in key areas like Java, Spring Boot, and front-end frameworks. Success requires both theoretical knowledge and practical experience building complete applications.
Solve the problem by thinking out loud to your interviewer which will help them trace your thought process. Before going to the solution, asking a clarifying question is always a good step. If you are not sure about the topic and have limited knowledge, be frank with the interviewer instead of trying to guess. If possible, link the answer with the real project that you have done. Enabling the learning process to work for you and showing it to the interviewer will definitely keep up the positive vibe.
Send thank-you email within 24 hours. Reflect on questions you struggled with and study those topics. Continue building projects and learning even while interviewing. Every interview is learning experience improving future performance.
To prepare effectively:
A Java Full Stack Developer should have:
Java Full Stack Developers should be familiar with both SQL and NoSQL databases (such as MySQL, PostgreSQL, MongoDB, Redis). Key concepts include:
NxtWave provides technology education and career development programs. Contact information: +919390111761 (WhatsApp only), [email protected]
Course Offerings: