<form method="post" action="validate">
    UserName:<input type="text" name="uname" />
    Password:<input type="text" name="pwd">
    <input type="submit" value="submit">
</form>

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet1 extends HttpServlet 
{
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException
    {
        response.setContentType("text/html");
        PrintWriter pw = response.getWriter();
    
        //getting value submitted in form from HTML file
        String user = request.getParameter("uname");
    
        //creating a new hidden form field
        pw.println("<form action='Second'>");
        pw.println("<input type='hidden' name='user' value='"+user+"'>");
        pw.println("<input type='submit' value='submit'>");
        pw.println("</form>");
    }
}

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class MyServlet2 extends HttpServlet
{
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException
    {
        response.setContentType("text/html");
        PrintWriter pw = response.getWriter();
        
        //getting parameter from the hidden field
        String user = request.getParameter("user");
        pw.println("Welcome "+user);
    }
}

<web-app...>
    <servlet>
        <servlet-name>First</servlet-name>
        <servlet-class>MyServlet1</servlet-class>
    </servlet>

    <servlet-mapping>
       <servlet-name>First</servlet-name>
       <url-pattern>/MyServlet1</url-pattern>
    </servlet-mapping>

    <servlet>
       <servlet-name>Second</servlet-name>
       <servlet-class>MyServlet2</servlet-class>
    </servlet>

    <servlet-mapping>
       <servlet-name>Second</servlet-name>
       <url-pattern>/MyServlet2</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
       <welcome-file>index.html</welcome-file>
    </welcome-file-list>
    
</web-app>