what the problem?

package login.pkgfinal;

import java.io.InputStream;







import java.util.logging.Level;







import java.util.logging.Logger;







import javafx.application.Application;







import javafx.fxml.FXMLLoader;







import javafx.fxml.Initializable;







import javafx.fxml.JavaFXBuilderFactory;







import javafx.scene.Scene;







import javafx.scene.layout.AnchorPane;







import javafx.stage.Stage;







import login.pkgfinal.login.model.User;







import login.pkgfinal.login.model.Admin;







import login.pkgfinal.login.security.Authenticator;







import java.sql.*;

public class Main extends Application {

private Stage stage;







private User loggedUser;







private final double MINIMUM_WINDOW_WIDTH = 390.0;







private final double MINIMUM_WINDOW_HEIGHT = 500.0;

public static void main(String[] args) {







Application.launch(Main.class, (java.lang.String[])null);







}

@Override







public void start(Stage primaryStage) throws ClassNotFoundException, SQLException {

Connection conn = null;







Statement stmt = null;







try{







//STEP 2: Register JDBC driver







Class.forName("com.mysql.jdbc.Driver");

//STEP 3: Open a connection







System.out.println("Connecting to database...");







Class.forName("com.mysql.jdbc.Driver");







conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/e_voting?zeroDateTimeBehavior=convertToNull","root ","");

//STEP 4: Execute a query







System.out.println("<?php ?>");







stmt = conn.createStatement();







String sql;







sql = "SELECT id, first, last, age FROM Employees";







ResultSet rs = stmt.executeQuery(sql);

stage = primaryStage;







stage.setTitle("Login Main");







stage.setMinWidth(MINIMUM_WINDOW_WIDTH);







stage.setMinHeight(MINIMUM_WINDOW_HEIGHT);







gotoLogin();







primaryStage.show();







} catch (Exception ex) {







Logger.getLogger(Main.class.getName()).log(Level.S EVERE, null, ex);







}







}

public User getLoggedUser() {







return loggedUser;







}







public boolean userLogging(String userId, String password){







if (Authenticator.validate(userId, password)) {







loggedUser = User.of(userId);







gotoPageVote();







return true;







} else {







return false;







}







}

void userLogout(){







loggedUser = null;







gotoLogin();







}

private void gotoPageVote() {







try {







PageVoteController pagevote = (PageVoteController) replaceSceneContent("PageVote.fxml");







pagevote.setApp(null);







} catch (Exception ex) {







Logger.getLogger(Main.class.getName()).log(Level.S EVERE, null, ex);







}







}

private void gotoLogin() {







try {







LoginController login = (LoginController) replaceSceneContent("Login.fxml");







login.setApp(null);







} catch (Exception ex) {







Logger.getLogger(Main.class.getName()).log(Level.S EVERE, null, ex);







}







}

private Initializable replaceSceneContent(String fxml) throws Exception {







FXMLLoader loader = new FXMLLoader();







InputStream in = Main.class.getResourceAsStream(fxml);







loader.setBuilderFactory(new JavaFXBuilderFactory());







loader.setLocation(Main.class.getResource(fxml));







AnchorPane page;







try {







page = (AnchorPane) loader.load(in);







} finally {







in.close();







}







Scene scene = new Scene(page, 800, 600);







stage.setScene(scene);







stage.sizeToScene();







return (Initializable) loader.getController();







}

}