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();

}

}