Untitled

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet("/zadanie_3")
public class Main extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        response.setContentType("text/html");
        response.setCharacterEncoding("UTF-8");
        PrintWriter writer = response.getWriter();

        try {
            int sum = (int) ((3 * (Math.pow(3, 2) + 1)) / 2);
            boolean check = true;
            int row = 0;
            int column = 0;
            int diagonal_r = 0;
            int diagonal_l = 0;
            for (int i = 0; i < 3; i++) {
                row = 0;
                column = 0;
                for (int j = 0; j < 3; j++) {
                    if (i == j) diagonal_r += Integer.parseInt(request.getParameter("value_" + (i + 1) + "_" + (i + 1)));
                    if (((i + 1) + (j + 1) - 1) == 3) diagonal_l += Integer.parseInt(request.getParameter("value_" + (i + 1) + "_" + (j + 1)));

                    column += Integer.parseInt(request.getParameter("value_" + (j + 1) + "_" + (i + 1)));
                    row += Integer.parseInt(request.getParameter("value_" + (i + 1) + "_" + (j + 1)));
                }

                if ((row != sum) || (column != sum)) check = false;
            }

            if ((diagonal_r != sum) || (diagonal_l != sum)) check = false;

            if (check) writer.println("<p style=\"color: green;\">Kwadrat jest magiczny</p>");
            else writer.println("<p style=\"color: red;\">Kwadrat nie jest magiczny</p>");
        } catch (Exception exception) {
            System.out.println("error");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        response.setContentType("text/html");
        response.setCharacterEncoding("UTF-8");
        PrintWriter writer = response.getWriter();

        writer.println("<html>");
        writer.println("<head>");
        writer.println("<title>Zadanie #3</title>");
        writer.println("</head>");
        writer.println("<body>");
        writer.println("<form action=\"/zadanie_3\" method=\"POST\">");
        writer.println("<table style=\"width:30%; border: 1px solid black; border-collapse: collapse;\">");

        String column = "<tr><th style=\"border: 1px solid black; border-collapse: collapse;\">X</th>";
        String row = "";
        for (int i = 0; i < 3; i++) {
            column += "<th style=\"border: 1px solid black; border-collapse: collapse;\">" + (i + 1) + "</th>";
            row += "<tr><td style=\"border: 1px solid black; border-collapse: collapse;\">" + (i + 1) + "</td>";
            for (int j = 0; j < 3; j++) {
                row += "<td style=\"border: 1px solid black; border-collapse: collapse;\"><input type=\"number\" name=\"value_" + (i + 1) + "_" + (j + 1) + "\"></td>";
            }
            row += "</tr>";
        }
        column += "</tr>";
        writer.println(column);
        writer.println(row);

        writer.println("</table>");
        writer.println("<br/><br/><input type=\"submit\" value=\"Sprawdź\">");
        writer.println("</form>");
        writer.println("</body>");
        writer.println("</html>");
    }
}