I am a beginner in Servlets so, trying to make a form and display the submitted data by clicking on the submit button. But for now, I have just printed "Welcome to Register form" but I am getting a 404 error not found.
I have tried several URLs in the action attribute of the HTML form:
But none of them resolved it.
RegisterServlet.java
package com. practice;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;
public class RegisterServlet extends HttpServlet {
    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("Started ..............");
        resp.setContentType("text/html");
        PrintWriter out = resp.getWriter();
        out.println("<h2> Welcome to Register form </h2>");   // This is the line which needs to get printed
    }
}
index.html (form layout)
    <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Servlet Form</title>
</head>
<style>
    body{
        background-color: bisque;
    }
    button{
        background-color: blue;
        color: aliceblue;
        padding: 11px 30px;
        border-radius: 10%;
        font-style: oblique;
        font-family: 'DejaVu Sans', Arial, Helvetica, sans-serif;
        font-weight: bold;
        font-size: medium;
    }
    .container{
        width: 40%;
        border: 5px solid black;
        margin: auto;
        padding: 20px;
        background-color: aliceblue;
        font-size: 18px;
    }
    #myform table tr td input{
        font-size: 20px;
    }
</style>
<body>
<div class = "container">
    <h1 style="text-align: center; font-style: italic">Welcome</h1>
<!--     post method is more secure than get method-->
    <form id="myform" action="RegisterServlet" method="post">
        <table>
            <tr>
                <td>Enter Your Full name</td>
                <td> <input type="text" name="user_name" placeholder="Enter Your Name"></td>
            </tr>
            <tr>
                <td>Enter Your Email-ID</td>
                <td> <input type="text" name="user_email" placeholder="Enter Your Email-ID"></td>
            </tr>
            <tr>
                <td>Enter Your Password</td>
                <td> <input type="text" name="user_pass" placeholder="Enter Your Password"></td>
            </tr>
            <tr>
                <td>Re-Enter Your Password</td>
                <td> <input type="text" name="user_pass" placeholder="Enter Your Password"></td>
            </tr>
            <tr>
                <td>Select Gender</td>
                <td> <input type="radio" name="user_gender" value="male" placeholder="Enter Your Gender">Male      <input type="radio" name="user_gender" value="female" placeholder="Enter Your Gender">Female</td>
            </tr>
            <tr>
                <td>Select Course</td>
                <td>
                    <select name="user_course">
                        <option value="java">JAVA</option>
                        <option value="android">Android Development</option>
                        <option value="web">Web Development</option>
                        <option value="ml">Machine Learning</option>
                        <option value="iot">IOT</option>
                    </select>
                </td>
            </tr>
            <tr>
                <td style="text-align: right"> <input type="checkbox" name="terms" value="checked"> </td>
                <td> <h3>  Please Agree to the Terms and Conditions </h3> </td>
            </tr>
            <tr>
                <td>
                </td>
                <td>
                    <button type="submit" class="button">SUBMIT</button>
                    <button type="reset" class="button">RESET</button>
                </td>
            </tr>
        </table>
    </form>
</div>
</body>
</html>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <servlet>
        <servlet-name>register</servlet-name>
        <servlet-class>com.practice.RegisterServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>register</servlet-name>
        <url-pattern>/RegisterServlet</url-pattern>
    </servlet-mapping>
</web-app>
index.jsp
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>Servlet Form</title>
  </head>
  <body>
  <h1>Hello</h1>
  </body>
</html>
