Servlet Interview Questions for Beginners and Experienced Developers

 

In the world of Java-based web development, Servlets play a crucial role. They act as the foundation for handling HTTP requests and responses in server-side Java applications. Whether you're just starting your career in Java web development or preparing for a senior-level role, understanding servlets is essential. In this blog, we’ve compiled a detailed list of servlet interview questions for both beginners and experienced developers to help you stay ahead in your technical interviews.

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What Is a Java Servlet?

Before we dive into the questions, let’s quickly refresh what a Java Servlet is.

A servlet is a Java program that runs on a web server or application server and handles requests from web clients, usually browsers. Servlets help build dynamic web content and serve as the backbone for Java web technologies like JSP, Spring MVC, and Struts.

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 Servlet Interview Questions for Beginners

Let’s begin with some basic questions that cover core concepts every beginner should know.

1. What is a Servlet?

A Servlet is a Java class that responds to HTTP requests and generates responses, typically in HTML format. It runs on a servlet container like Apache Tomcat.

2. What are the advantages of using Servlets?

• Platform-independent

• Efficient and scalable

• Better performance compared to CGI

• Robust with built-in support for multithreading

• Easy integration with Java-based technologies

3. What is the servlet lifecycle?

The servlet lifecycle consists of three main methods:

• init() – Called once when the servlet is initialized

• service() – Called for each request

• destroy() – Called when the servlet is being taken out of service

These methods are defined by the javax.servlet.Servlet interface.

4. What is the difference between GET and POST methods?

• GET: Appends data to the URL and is visible in the browser address bar. It’s suitable for fetching data.

• POST: Sends data in the request body, making it more secure. It’s used for updating or submitting data.

5. What is the web.xml file used for?

web.xml, also known as the deployment descriptor, is used to configure servlet mappings, initialization parameters, welcome files, and error pages. It defines how requests should be handled by servlets.

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 Servlet Interview Questions for Experienced Developers

If you're applying for mid or senior-level roles, expect more in-depth questions around servlet architecture, request handling, and integration.

6. What is the role of the HttpServlet class?

HttpServlet is a subclass of GenericServlet provided by the Java Servlet API. It provides methods like doGet(), doPost(), and doPut() to handle HTTP-specific requests.

7. How does session management work in servlets?

There are four main ways to manage sessions:

• Cookies: Store user data on the client side

• Hidden form fields: Embed session data in HTML forms

• URL rewriting: Append session ID to URLs

• HttpSession: Server-side session tracking using HttpSession object

8. How can you forward a request to another resource in a servlet?

You can use RequestDispatcher:

java
RequestDispatcher rd = request.getRequestDispatcher("anotherServlet");
rd.forward(request, response);

This helps delegate request processing to another servlet or JSP.

9. What’s the difference between forward() and sendRedirect()?

• forward() is performed server-side and doesn’t change the URL in the browser.

• sendRedirect() is client-side and tells the browser to make a new request to a different URL.

10. What is the purpose of filters in servlets?

Filters are used for tasks such as logging, authentication, input validation, and response compression. They intercept requests and responses before they reach the servlet or client.

11. How do you handle exceptions in servlets?

You can handle exceptions using:

• Try-catch blocks within your servlet

• <error-page> entries in web.xml for global error handling

• Custom error-handling filters or listeners

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 Servlet vs JSP: What’s the Difference?

A frequently asked servlet interview question revolves around the difference between Servlets and JSP:

• Servlets are Java programs and better suited for business logic

• JSP (JavaServer Pages) are better for presentation logic with HTML templates

Together, they follow the MVC (Model-View-Controller) pattern to separate logic and design.

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 Bonus Tips to Ace Servlet Interviews

• Practice hands-on: Set up a local Tomcat server and build small applications using servlets.

• Understand the API: Get familiar with packages like javax.servlet and javax.servlet.http.

• Explore advanced topics: Learn about servlet listeners, annotations (like @WebServlet), and async processing.

• Combine with frameworks: Be ready to explain how servlets integrate with Spring or JSP in enterprise projects.

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 Final Thoughts

Understanding servlets is key for Java web development, especially when working with legacy systems or building custom backend logic. Whether you're just beginning your journey or stepping into a more advanced role, these servlet interview questions will help you prepare thoughtfully for any level of interview.

Remember, knowing the theory is important, but practical experience with building and deploying servlets in real-world applications will set you apart in interviews.