Es 18 su JSP

<%-- 
    Document   : index
    Created on : 12-dic-2017, 21.55.42
    Author     : GfO
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Quadrati da n1 a n2</title>
    </head>
    <body>
        <h1>Quadrati da n1 a n2</h1>
        <form action="index.jsp" method="get">
            n1: <input name="n1" type="text">
            n2: <input name="n2" type="text">
            <input type="submit" value="Invia">
        </form>
        <%
            String n1str = request.getParameter("n1");
            String n2str = request.getParameter("n2");

            if (n1str != null && n2str != null)
                try {
                    int n1 = Integer.parseInt(n1str);
                    int n2 = Integer.parseInt(n2str);
        %>
        <table>
            <% for (int i = n1; i <= n2; i++) { %>
            <tr><td> <%=i%> </td><td> <%=i * i%> </td></tr>
            <% } // end for %>
        </table>
        <% } catch (Exception e) { %>
        <p>Devi inserire due numeri validi</p>
        <% } // end try-catch %>
    </body>
</html>