Untitled

package matematika;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Objects;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author qasko
 */
@WebServlet(name = "Main", urlPatterns = {"/Main"})
public class Main extends HttpServlet {

    private ArrayList<Integer> correctResults;
    private ArrayList<Integer> userResults;
    private ArrayList<String> arrayList;

    private final String driver = "com.mysql.jdbc.Driver";
    private Connection con = null;
    private Statement stmt = null;
    private ResultSet rs = null;
    private final String username = "root";
    private final String password = "";
    private final String URL = "jdbc:mysql://localhost/math";

    private int MIN_NUMBER;
    private int MAX_NUMBER;

    private int a;
    private int b;
    private int c;

    private int count;

    private String o;

    @Override
    public void init() throws ServletException {

        super.init();

        try {
            Class.forName(driver);
            con = DriverManager.getConnection(URL, username, password);
        } catch (ClassNotFoundException | SQLException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }

        try {
            stmt = con.createStatement();
            rs = stmt.executeQuery("select count from problems_count");
            rs.next();
            count = rs.getInt(1);
        } catch (SQLException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }

        correctResults = new ArrayList<>();
        userResults = new ArrayList<>();
        arrayList = new ArrayList<>();

        MIN_NUMBER = 0;
        MAX_NUMBER = 100;

        a = 0;
        b = 0;
        c = 0;

        o = null;
    }

    public int randInt(int min, int max) {
        Random rand = new Random();

        int randomNum = rand.nextInt((max - min) + 1) + min;

        return randomNum;
    }

    public int mathProblem() {

        int plusMinus = randInt(0, 1);

        if (plusMinus == 0) {
            a = randInt(MIN_NUMBER, MAX_NUMBER);
            b = randInt(MIN_NUMBER, MAX_NUMBER);

            while ((a + b) > 100) {
                a = randInt(MIN_NUMBER, MAX_NUMBER);
                b = randInt(MIN_NUMBER, MAX_NUMBER);
            }

            c = a + b;
            o = "+";

            //kontrola
            System.out.println(a + o + b + "=" + c);

            //listy
            correctResults.add(c);
            arrayList.add(a + " " + o + " " + b + " = ");

            return c;
        } else {
            a = randInt(MIN_NUMBER, MAX_NUMBER);
            b = randInt(MIN_NUMBER, a);
            c = a - b;
            o = "-";
            System.out.println(a + o + b + "=" + c);

            //listy
            correctResults.add(c);
            arrayList.add(a + " " + o + " " + b + " = ");

            return c;
        }
    }

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {

            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet Main</title>");
            out.println("<link rel=\"stylesheet\" href=\"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/css/bootstrap.min.css\" integrity=\"sha384-y3tfxAZXuh4HwSYylfB+J125MxIs6mR5FOHamPBG064zB+AFeWH94NdvaCBm8qnd\" crossorigin=\"anonymous\">");
            out.println("</head>");
            out.println("<body>");
            out.println("<div style='margin-top: 5em' class='container'>");

            if (request.getContentType() != null) {

                String button = request.getParameter("button");

                double correct = 0;

                if (button.equals("Check")) {

                    out.println("<div class='row'>");

                    for (int i = 0; i < count; i++) {

                        out.println("<div class='col-md-6'>");

                        try {
                            userResults.add(Integer.parseInt(request.getParameter("problem" + i)));
                        } catch (NumberFormatException ex) {
                            userResults.add(0);
                        }

                        if (Objects.equals(userResults.get(i), correctResults.get(i))) {
                            out.println("<p><h3 style='color: green'>" + arrayList.get(i) + userResults.get(i) + "</h3></p>"); //spravne
                            correct++;
                        } else {
                            out.println("<p><h3 style='color: red'>" + arrayList.get(i) + correctResults.get(i) + " (" + userResults.get(i) + ")</h3></p>"); //nespravne
                        }

                        out.println("</div>");
                    }

                    out.println("<h2><div class='col-md-12'><hr>Success: " + Math.round((correct / count) * 100) + "%</div></h2>");

                    out.println("</div>");
                }

            }

            if (request.getContentType() == null) {

                arrayList.clear();
                correctResults.clear();
                userResults.clear();

                for (int i = 0; i < count; i++) {
                    mathProblem();
                }

                out.println("<form action='Main' method='post'>");
                out.println("<div class='row'>");

                for (int i = 0; i < arrayList.size(); i++) {
                    out.println("<div class='col-md-6'>");
                    out.println("<fieldset class='form-group'>");
                    out.println("<label for='problem" + i + "'>" + arrayList.get(i) + "</label>");
                    out.println("<input type='text' class='form-control' id='problem" + i + "' name='problem" + i + "'>");
                    out.println("</fieldset></div>");
                }

                out.println("<div class='col-md-12'><input class='btn btn-primary' type='submit' value='Check' name='button'></div>");
                out.println("</form>");
            }

            out.println("</div></div>");

            out.println("<script src=\"https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js\"></script>\n"
                    + "<script src=\"https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/js/bootstrap.min.js\" integrity=\"sha384-vZ2WRJMwsjRMW/8U7i6PWi6AlO1L79snBrmgiDpgIWJ82z8eA5lenwvxbMV1PAh7\" crossorigin=\"anonymous\"></script>");
            out.println("</body>");
            out.println("</html>");
        }

    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}