Advanced Java Interview Questions

• What is JDBC?
  JDBC stands for Java Database Connectivity, used to connect and manipulate databases.
• What is servlet?
  Servlet is a Java program that runs on a web or application server, handling client requests.
• What is JSP?
  JSP stands for Java Server Pages, combining HTML and JSP tags to create dynamic web content.
• What is the life cycle of servlet?
  The servlet life cycle includes init(), service(), and destroy() methods.
• What are the steps to create JDBC connection?
  Steps include importing packages, registering drivers, establishing connections, creating statements, executing queries, retrieving results, and closing connections.
• When is the destroy() method of servlet called?
  It is called once at the end of the servlet's life cycle.
• What are the different types of statements in JDBC?
  Statement, PreparedStatement, and CallableStatement.
• What is the difference between execute(), executeQuery(), and executeUpdate() in JDBC?
  execute() returns a boolean, executeQuery() returns a ResultSet, and executeUpdate() returns an integer.
• What is the difference between ServletConfig and ServletContext?
  ServletConfig is for servlet-specific init parameters, while ServletContext is for application-wide init parameters.
• How to create Statement and PreparedStatement interfaces in JDBC?
  Example code is provided for creating these interfaces.
• Can you create a Deadlock condition on a servlet?
  Yes, a deadlock can be created by calling doPost() inside doGet() or vice versa.
• What is the difference between sendRedirect() and RequestDispatcher?
  Detailed differences and usage examples are explained.
• How to delete and create cookies using servlets?
  Steps for deleting and creating cookies are provided with examples.
• What is URL Rewriting?
  Explanation of how URL rewriting works.
• How to read data in servlets?
  Methods like getParameter(), getParameterValues(), and getParameterNames() are explained.
• What is Cookie?
  Explanation of what a cookie is and its properties.
• What are the annotations used in Servlet 3?
  Annotations like @WebServlet, @WebListener, and @WebFilter.
• What is the use of RequestDispatcher Interface?
  Explanation of how RequestDispatcher forwards and includes requests.
• Why do we use sendRedirect() method?
  Explanation of when to use sendRedirect() and its purpose.
• What are the differences between ResultSet and RowSet?
  Differences in behavior and serialization capabilities between ResultSet and RowSet.
• What are the methods used in the lifecycle of JSP?
  Methods like jspInit(), _jspService(), and jspDestroy() are explained.
• What is MVC?
  Explanation of the Model-View-Controller architecture.
• What is the use of <jsp:include> tag?
  Explanation of how the <jsp:include> tag works.
• What is the use of <welcome-file-list> tag?
  Explanation of defining default welcome files in web.xml.
• What is the use of <servlet-mapping> tag?
  Explanation of mapping servlets to URL patterns in web.xml.
• What is <session-config>?
  Explanation of session configuration in web.xml.
• What is session timeout in web.xml of JSP?
  Explanation of setting session timeout in web.xml.
• What is the use of <class-name> tag in web.xml?
  Explanation of specifying servlet class names in web.xml.
• What is a custom tag in JSP?
  Explanation of user-defined tags and their benefits.
• What is the difference between doGet() and doPost()?
  Differences between HTTP GET and POST methods in servlets.
• Can you disable caching on the back button of a particular browser?
  Explanation of how to disable caching using response headers.
• What are the methods available in the session object?
  List of methods available in the HttpSession interface.
• What is the role of Class.forName() while loading drivers?
  Explanation of how Class.forName() is used to load JDBC drivers.
• Why does "No suitable driver" error occur?
  Explanation of common causes of JDBC driver errors.
• What are the exceptions in JDBC?
  List of common exceptions in JDBC like SQLException.
• Give steps to connect to the DB using JDBC?
  Steps for connecting to a database using DriverManager and DataSource.
• What is a DataSource in JDBC?
  Explanation of how DataSource objects provide connections from connection pools.
• How many ways can you update a result set?
  Methods like updateRow(), deleteRow(), and insertRow() for updating result sets.
• How to set the attribute Concurrency in ResultSet?
  Explanation of setting concurrency levels for ResultSet.
• What are the methods available in HttpServlet class?
  List of methods available in the HttpServlet class for handling HTTP requests.
• What is HTTPFilter?
  Explanation of HTTP filters and their use in servlets.
• How is servlet filter configuration done in web.xml?
  Syntax and example of configuring servlet filters in web.xml.
• What are the uses of filter in servlets?
  Common uses of servlet filters like logging, encryption, and validation.
• What are the methods available in the Filter interface in servlets?
  List of methods available in the javax.servlet.Filter interface.
• What is the difference between war file and jar file?
  Differences between WAR (Web Archive) and JAR (Java Archive) files.
• How to create a war file?
  Steps for creating a .war file using the jar tool.
• What is ServletInputStream?
  Explanation of ServletInputStream for reading binary data from requests.
• What is ServletOutputStream?
  Explanation of ServletOutputStream for writing binary data to responses.
• What are the methods available in ServletOutputStream class?
  List of methods available in ServletOutputStream for writing various data types.
• Explain SingleThreadModel interface?
  Explanation of SingleThreadModel interface and its usage in servlets.
• What are the methods available in ServletContext Interface?
  List of methods available in the ServletContext interface for managing servlet contexts.
• How to get the object of ServletContext interface?
  Example of getting ServletContext object using getServletContext() method.
• What are Techniques of Session Tracking?
  Different techniques for session tracking in servlets like cookies, URL rewriting, and HttpSession.
• Explain JDBC URL connection for Oracle and MySQL?
  JDBC URL formats for connecting to Oracle and MySQL databases.
• How to establish connection using the Connection class Object?
  Steps for establishing a JDBC connection using the Connection class.
• What is J2EE?
  Explanation of Java 2 Platform, Enterprise Edition (J2EE) architecture and components.
• What is the use of DriverManager class in JDBC?
  Explanation of how DriverManager class manages JDBC drivers.
• How to integrate a Servlet with JSP?
  Steps for integrating servlets with JSP for dynamic web content.
• What is the use of getParameter() method in servlets?
  Explanation of how to retrieve request parameters in servlets.
• What are the differences between doGet() and doPost() methods in servlets?
  Differences in usage and handling of HTTP GET and POST requests in servlets.
• How to use forward action in a JSP?
  Explanation of how to use forward action to include content from another resource in JSP.
• What is the use of @WebServlet annotation?
  Explanation of @WebServlet annotation for defining servlets in Java EE web applications.
• How to perform exception handling in servlets?
  Techniques for handling exceptions in servlets using try-catch blocks and error pages.
• What are the advantages of Servlet over CGI?
  Advantages like performance, efficiency, and scalability of servlets over CGI scripts.
• What is the difference between forward() method and sendRedirect() method?
  Differences in usage and behavior of forward() and sendRedirect() methods in servlets.
• How to upload files in servlets?
  Steps for handling file uploads in servlets using multipart/form-data and Apache Commons FileUpload.
• What is the use of servlet container?
  Explanation of servlet containers like Apache Tomcat for executing servlets and managing their life cycle.
• What is the use of Servlet Collaboration?
  Explanation of servlet collaboration techniques like RequestDispatcher and include action.
• What is the difference between servlets and applets?
  Differences between servlets and applets in terms of execution environment, usage, and deployment.
• What is the use of @WebFilter annotation?
  Explanation of @WebFilter annotation for defining filters in Java EE web applications.
• How to handle HTML form data in servlets?
  Techniques for retrieving and processing form data submitted to servlets using HttpServletRequest.
• What is the use of JSTL?
  Explanation of JSTL (JavaServer Pages Standard Tag Library) for simplifying JSP development with reusable tags.
• What is the use of <form> tag in HTML?
  Explanation of <form> tag for creating HTML forms to submit user input to server-side applications.
• How to use PrintWriter object in servlets?
  Techniques for using PrintWriter object to send output from servlets to client browsers.
• What is the use of session tracking?
  Explanation of session tracking techniques like cookies, URL rewriting, and HttpSession for maintaining user state.
• What is the use of JDBC DriverManager class?
  Explanation of DriverManager class for managing JDBC drivers and establishing database connections.
• How to integrate servlets with JDBC?
  Steps for integrating servlets with JDBC to interact with databases and perform CRUD operations.
• What are the components of Java EE architecture?
  Explanation of Java EE architecture components like web containers, EJB containers, and application clients.
• What is the use of HttpSession in servlets?
  Explanation of HttpSession for maintaining user session state across multiple requests in servlets.
• What are the advantages of servlets over CGI?
  Advantages like performance, scalability, and platform independence of servlets over CGI scripts.
• How to handle exceptions in servlets?
  Techniques for exception handling in servlets using try-catch blocks, error pages, and logging.
• What is the use of servlet context?
  Explanation of servlet context for sharing global information and resources across servlets in a web application.
• How to perform form validation in servlets?
  Techniques for validating HTML form data submitted to servlets using JavaScript, server-side validation, and error messages.
• What is the use of @WebListener annotation?
  Explanation of @WebListener annotation for defining listener classes to handle application and session events in Java EE web applications.
• How to handle session management in servlets?
  Techniques for managing HTTP session state in servlets using HttpSession, cookies, and URL rewriting.
• What are the advantages of JDBC PreparedStatement over Statement?
  Advantages like improved performance, security, and prevention of SQL injection attacks with PreparedStatement in JDBC.
• What is the use of @WebServlet annotation in servlets?
  Explanation of @WebServlet annotation for defining servlets in Java EE web applications with URL mappings and initialization parameters.
• How to configure servlet filters in web.xml?
  Steps for configuring servlet filters in web.xml to intercept and manipulate requests and responses in Java EE web applications.
• What is the use of servlet container?
  Explanation of servlet container like Apache Tomcat for executing servlets, managing their life cycle, and providing runtime environment for Java EE web applications.
• What are the differences between forward() and sendRedirect() methods in servlets?
  Differences in usage and behavior of forward() and sendRedirect() methods for forwarding requests to another resource or URL in Java EE web applications.
• How to handle file uploads in servlets?
  Techniques for handling file uploads in servlets using multipart/form-data encoding, Apache Commons FileUpload library, and processing file data in Java EE web applications.
• What is the use of ServletOutputStream in servlets?
  Explanation of ServletOutputStream for writing binary data, such as file downloads or image streams, to HTTP response output streams in Java EE web applications.
• What are the advantages of servlets over applets?
  Advantages like server-side execution, platform independence, enhanced performance, and access to server resources for servlets compared to client-side applets in Java EE web applications.
• What is the use of @WebFilter annotation in servlets?
  Explanation of @WebFilter annotation for defining servlet filters to intercept and manipulate requests and responses based on URL patterns or servlet mappings in Java EE web applications.
• How to handle HTML form data submission in servlets?
  Techniques for handling HTML form data submission in servlets using HttpServletRequest methods, such as getParameter() and getParameterValues(), to retrieve form input values and process form submissions in Java EE web applications.
• What is the use of JSP Standard Tag Library (JSTL) in servlets?
  Explanation of JSP Standard Tag Library (JSTL) for simplifying JSP page development by providing reusable tags and functions for common tasks, such as iteration, conditionals, formatting, and internationalization, in Java EE web applications.
• How to use PrintWriter object in servlets for response generation?
  Techniques for using PrintWriter object in servlets to generate HTTP response content, such as HTML markup, text output, or JSON data, for client-side rendering or data consumption in Java EE web applications.
• What is the use of session tracking in servlets?
  Explanation of session tracking techniques, such as cookies, URL rewriting, and HTTP session objects, for maintaining user state and session management across multiple requests and interactions in Java EE web applications.
• What is the use of JDBC DriverManager class in servlets?
  Explanation of JDBC DriverManager class in servlets for managing JDBC driver registration, database connection establishment, and data access operations, such as executing SQL queries, transactions, and result set processing, in Java EE web applications.
• How to integrate servlets with JDBC for database interaction?
  Techniques for integrating servlets with JDBC to interact with relational databases, such as MySQL, Oracle, or PostgreSQL, by executing SQL statements, processing query results, and handling database transactions in Java EE web applications.
• What are the components of Java EE architecture for servlet development?
  Explanation of Java EE architecture components, such as web containers, EJB containers, application clients, and resource adapters, for developing servlet-based web applications with scalable, robust, and distributed deployment models in enterprise environments.
• What is the use of HttpSession interface in servlets for session management?
  Explanation of HttpSession interface in servlets for managing HTTP session state, such as session attribute storage, retrieval, modification, and removal, to maintain user-specific data and interactions across multiple requests and sessions in Java EE web applications.
• What are the advantages of servlets over CGI scripts for web application development?
  Advantages of servlets over CGI scripts, such as improved performance, scalability, server-side execution model, platform independence, and efficient resource utilization, for developing dynamic, interactive, and responsive web applications in Java EE environments.
• How to handle exceptions in servlets for error handling and debugging?
  Techniques for handling exceptions in servlets, such as try-catch blocks, exception propagation, custom error pages, logging mechanisms, and stack trace analysis, for effective error handling, debugging, and troubleshooting in Java EE web applications.
• What is the use of servlet context in Java EE for web application development?
  Explanation of servlet context in Java EE for sharing global configuration settings, resources, and application-wide parameters across multiple servlets, filters, listeners, and JSP pages within a web application environment for centralized management and access control.
• How to perform form validation in servlets for user input verification?
  Techniques for performing form validation in servlets, such as client-side validation using JavaScript, server-side validation with servlet request parameters, validation logic implementation, error message generation, and feedback display for user input verification in Java EE web applications.
• What is the use of @WebListener annotation in servlets for event handling?
  Explanation of @WebListener annotation in servlets for defining listener classes to handle application, session, request, and context lifecycle events, such as initialization, destruction, attribute changes, and session activation, in Java EE web applications for event-driven programming and event handling.
• How to manage session state in servlets using HttpSession interface for session tracking?
  Techniques for managing session state in servlets using HttpSession interface, such as session attribute storage, retrieval, modification, removal, session timeout configuration, session tracking mechanisms, and session management strategies for maintaining user-specific data and interactions in Java EE web applications.
• What are the advantages of JDBC PreparedStatement over Statement for database interaction in servlets?
  Advantages of JDBC PreparedStatement over Statement for database interaction in servlets, such as SQL injection prevention, performance optimization, query execution plan caching, parameterized query support, automatic data type conversion, and enhanced security features for efficient and secure data access operations in Java EE web applications.
• What is the use of @WebServlet annotation in servlets for URL mapping and initialization?
  Explanation of @WebServlet annotation in servlets for defining servlet classes with URL patterns, display names, load-on-startup configurations, initialization parameters, and servlet metadata annotations for URL mapping, request handling, servlet lifecycle management, and runtime configuration in Java EE web applications.
• How to configure servlet filters in web.xml for request and response manipulation?
  Techniques for configuring servlet filters in web.xml deployment descriptor to intercept, process, manipulate, filter, and enhance HTTP request and response objects, such as URL rewriting