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Servlet Interview Questions


  • What is a Servlet?
    Answer: A Servlet is a Java program that extends the capabilities of a web server to generate dynamic content in response to client requests.

  • What is the life cycle of a Servlet?
    Answer: The life cycle of a Servlet consists of four stages: initialization, service, destruction, and garbage collection.

  • What are the methods of the Servlet interface?
    Answer: The methods of the Servlet interface are init(), service(), and destroy().

  • What is the purpose of the init() method?
    Answer: The init() method is used to initialize the Servlet and is called only once in its life cycle.

  • What is the purpose of the service() method?
    Answer: The service() method is used to handle client requests and is called every time a request is made to the Servlet.

  • What is the purpose of the destroy() method?
    Answer: The destroy() method is used to clean up any resources used by the Servlet and is called only once in its life cycle.

  • What is a Servlet container?
    Answer: A Servlet container is a web server that implements the Servlet API and is responsible for managing the life cycle of Servlets.

  • What is the difference between a Servlet and a JSP?
    Answer: A Servlet is a Java program that generates dynamic content, while a JSP is a markup language that allows Java code to be embedded in HTML.

  • What is a Servlet filter?
    Answer: A Servlet filter is a Java program that intercepts incoming requests and outgoing responses and can perform various operations on them.

  • What is the purpose of the HttpServletRequest object?
    Answer: The HttpServletRequest object provides information about the client's request, such as the HTTP method, headers, and parameters.

  • What is the purpose of the HttpServletResponse object?
    Answer: The HttpServletResponse object provides methods to generate a response to the client, such as setting the status code, headers, and content.

  • What is a Servlet session?
    Answer: A Servlet session is a way to maintain state between client requests by storing data on the server and associating it with a unique session ID.

  • What is the purpose of the ServletContext object?
    Answer: The ServletContext object provides information about the web application and can be used to share data between Servlets.

  • What is the purpose of the @WebServlet annotation?
    Answer: The @WebServlet annotation is used to declare a Servlet in a web application and can be used to specify its URL mapping, initialization parameters, and other attributes.

  • What is the purpose of the ServletContextListener interface?
    Answer: The ServletContextListener interface is used to receive notifications when the Servlet context is initialized and destroyed.

  • What is the purpose of the ServletRequestListener interface?
    Answer: The ServletRequestListener interface is used to receive notifications when a request is initialized and destroyed.

  • What is the purpose of the ServletRequestAttributeListener interface?
    Answer: The ServletRequestAttributeListener interface is used to receive notifications when an attribute is added, removed, or replaced in the HttpServletRequest.

  • What is connection pooling in Servlets?
    Answer: Connection pooling is a technique used to improve the performance of a web application by reusing database connections instead of creating a new one for every request.

  • What is the purpose of the FilterChain interface?
    Answer: The FilterChain interface is used to chain multiple Servlet filters together and can be used to pass the request and response between them.
  • What is the difference between a doGet() and doPost() method?
    Answer: The doGet() method is used to handle HTTP GET requests, while the doPost() method is used to handle HTTP POST requests.

  • What is the purpose of the Session interface?
    Answer: The Session interface provides methods to manage and retrieve data associated with a Servlet session.

  • What is the difference between a session and a cookie?
    Answer: A session is a way to maintain state between client requests by storing data on the server, while a cookie is a way to maintain state by storing data on the client's browser.

  • What is a Servlet container and what are its responsibilities?
    Answer: A Servlet container is a web server that implements the Servlet API and is responsible for managing the life cycle of Servlets, handling requests and responses, and providing other services such as security and JSP support.

  • What is the purpose of the HttpServletRequestWrapper and HttpServletResponseWrapper classes?
    Answer: These classes are used to extend the functionality of the HttpServletRequest and HttpServletResponse objects by providing additional methods and allowing customization of the request and response.

  • What is the purpose of the @WebFilter annotation?
    Answer: The @WebFilter annotation is used to declare a Servlet filter in a web application and can be used to specify its URL mapping, initialization parameters, and other attributes.

  • What is a Servlet container thread pool?
    Answer: A thread pool is a group of threads that are created and managed by the Servlet container and are used to handle client requests. This can improve performance by avoiding the overhead of creating a new thread for every request.

  • What is the purpose of the HttpServletRequestWrapper and HttpServletResponseWrapper classes?
    Answer: These classes are used to extend the functionality of the HttpServletRequest and HttpServletResponse objects by providing additional methods and allowing customization of the request and response.

  • What is the purpose of the HttpSessionActivationListener interface?
    Answer: The HttpSessionActivationListener interface is used to receive notifications when a session is activated or passivated, which occurs when the session is either bound to or unbound from the server.

  • What is the purpose of the HttpSessionBindingListener interface?
    Answer: The HttpSessionBindingListener interface is used to receive notifications when an object is bound to or unbound from a session.

  • What is the difference between a forward() and include() method in the RequestDispatcher interface?
    Answer: The forward() method is used to transfer control to another resource, while the include() method is used to include the content of another resource in the response.

  • What is a Servlet context attribute?
    Answer: A Servlet context attribute is an object that is associated with the ServletContext object and can be used to share data between Servlets in the same web application.

  • What is a Servlet response buffer?
    Answer: A Servlet response buffer is a memory buffer used to temporarily store the content of the response before it is sent to the client.

  • What is the difference between a Filter and a Servlet?
    Answer: A Filter is a component that intercepts requests and responses and can perform operations on them, while a Servlet is a component that generates dynamic content in response to client requests.

  • What is the purpose of the ServletRequest interface?
    Answer: The ServletRequest interface provides methods to retrieve information about the client's request, such as the protocol, URL, headers, and parameters.
  • What is a Servlet API?
    Answer: The Servlet API is a set of Java classes and interfaces that provide a framework for building web applications.

  • What is the difference between a Servlet and a JSP?
    Answer: A Servlet is a Java class that generates dynamic content in response to client requests, while a JSP is a text file that contains a combination of HTML and Java code.

  • What is the purpose of the ServletContextListener interface?
    Answer: The ServletContextListener interface is used to receive notifications when the Servlet context is created or destroyed.

  • What is the purpose of the ServletContextAttributeListener interface?
    Answer: The ServletContextAttributeListener interface is used to receive notifications when an attribute is added, removed, or replaced in the Servlet context.

  • What is a filter chain in a Servlet?
    Answer: A filter chain is a series of filters that are applied to a request in sequence.

  • What is the purpose of the @WebListener annotation?
    Answer: The @WebListener annotation is used to declare a Servlet context listener, attribute listener, or session listener in a web application.

  • What is the purpose of the @WebServlet annotation?
    Answer: The @WebServlet annotation is used to declare a Servlet in a web application and can be used to specify its URL mapping, initialization parameters, and other attributes.

  • What is the difference between a ServletContext and a ServletRequest?
    Answer: The ServletContext object represents the entire web application, while the ServletRequest object represents a single client request.

  • What is the purpose of the @WebInitParam annotation?
    Answer: The @WebInitParam annotation is used to specify initialization parameters for a Servlet, Filter, or Listener in a web application.

  • What is the difference between a Cookie and a Session?
    Answer: A Cookie is a small text file that is stored on the client's browser and can be used to maintain state between client requests, while a Session is a server-side object that can be used to maintain state between client requests.

  • What is the difference between a GET and a POST request?
    Answer: A GET request is used to retrieve data from the server, while a POST request is used to submit data to the server.

  • What is a Dispatcher in a Servlet?
    Answer: A Dispatcher is an object that is used to transfer control from one Servlet to another or from a Servlet to a JSP.

  • What is the purpose of the ServletResponseWrapper class?
    Answer: The ServletResponseWrapper class is used to extend the functionality of the ServletResponse object by providing additional methods and allowing customization of the response.

  • What is the purpose of the ServletRequestAttributeListener interface?
    Answer: The ServletRequestAttributeListener interface is used to receive notifications when an attribute is added, removed, or replaced in the ServletRequest object.

  • What is the difference between a Redirect and a Forward in a Servlet?
    Answer: A Redirect is used to send a client to a different URL, while a Forward is used to transfer control to another Servlet or JSP within the same web application.

  • What is the purpose of the HttpSessionListener interface?
    Answer: The HttpSessionListener interface is used to receive notifications when a session is created or destroyed.
  • What is the difference between include() and forward() methods in a Servlet?
    Answer: include() includes the content of the target resource in the response, whereas forward() transfers the control to the target resource without returning back to the caller.

  • What is the use of init() method in a Servlet?
    Answer: The init() method is used to initialize the Servlet, and is called only once in the lifetime of the Servlet.

  • What is a Servlet container?
    Answer: A Servlet container is a web server that provides an environment to run Servlets and manage their lifecycle.

  • What is the purpose of the RequestDispatcher interface?
    Answer: The RequestDispatcher interface is used to forward the request from one Servlet to another Servlet or a JSP.

  • What is the difference between doGet() and doPost() methods in a Servlet?
    Answer: doGet() method is used to handle HTTP GET requests, whereas doPost() method is used to handle HTTP POST requests.

  • What is the difference between ServletContext and HttpSession?
    Answer: ServletContext represents the entire web application and is created once during the application startup, whereas HttpSession represents a specific user session and is created every time a user requests a page.

  • What is the purpose of the ServletResponse interface?
    Answer: The ServletResponse interface is used to send response to the client.

  • What is the use of destroy() method in a Servlet?
    Answer: The destroy() method is used to clean up the resources used by the Servlet, and is called only once during the lifecycle of the Servlet.

  • What is a web.xml file in a Servlet?
    Answer: The web.xml file is a deployment descriptor for a web application that contains information about the Servlets, Filters, and Listeners used in the application.

  • What is a Servlet context?
    Answer: A Servlet context is an object that provides information about the Servlet environment and is created once during the application startup.

  • What is the use of getParameter() method in a Servlet?
    Answer: The getParameter() method is used to retrieve the value of a parameter passed in the request.

  • What is the use of setContentType() method in a Servlet?
    Answer: The setContentType() method is used to set the content type of the response.

  • What is the purpose of the @WebFilter annotation?
    Answer: The @WebFilter annotation is used to declare a Filter in a web application and can be used to specify its URL mapping, initialization parameters, and other attributes.

  • What is the purpose of the ServletContextAttributeEvent class?
    Answer: The ServletContextAttributeEvent class is used to represent an event that occurs when an attribute is added, removed, or replaced in the Servlet context.

  • What is the purpose of the HttpSession interface?
    Answer: The HttpSession interface is used to maintain session information for a client.

  • What is the purpose of the @WebResult annotation?
    Answer: The @WebResult annotation is used to specify the output parameter of a web service method.

  • What is a Servlet request?
    Answer: A Servlet request is an object that provides information about the client's request and is created every time a client sends a request.

  • What is a Servlet response?
    Answer: A Servlet response is an object that provides a mechanism to send response back to the client.


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