Demo.java:
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet("/Demo")
public class Demo extends HttpServlet {
	private static final long serialVersionUID = 1L;
    
    public Demo() {
        super();
        
    }

	
    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        // Initialization code here
        System.out.println("Servlet init() method called.");
    }


    @Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        // Handle request
        System.out.println("Servlet service() method called.");
        super.service(req, res);
    }
    @Override
    public void destroy() {
        // Cleanup code here
        System.out.println("Servlet destroy() method called.");
    }

}

web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>Demo1</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.jsp</welcome-file>
    <welcome-file>default.htm</welcome-file>
  </welcome-file-list>
</web-app>