Java Navigation System for GUI in JavaFX

I am currently working on a project in Java, and I use JavaFX for the GUI of the System. Currently, I am in the designing phase of the system, where I am designing the look of the system as well as setting up the basic functionality like navigation. I would highly appreciate it if someone can review my simple navigation system and the code I have written so far. I would like to know:

• Any bad practices I am following, and how would I improve them.
• Any architectural issues in my program, and how would I rectify that issue.
• Any techniques I could follow to keep my software more maintainable.
• Any inefficiencies that can be optimised.
• And any sort of points you have in your mind that I could follow to improve my software.
• Anything that you can add to the list above would also highly help.

I also have a preloader for this application, I have provided the code just for the sake of completeness. This preloader was generated by NetBeans.

TeleMart_Preloader.java

/*
 * Program developed by Hassan Althaf.
 * Copyright © 2015, Hassan Althaf.
 * Website: http://hassanalthaf.com
 */
package telemart.preloader;

import javafx.application.Preloader;
import javafx.application.Preloader.ProgressNotification;
import javafx.application.Preloader.StateChangeNotification;
import javafx.scene.Scene;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

/**
 * Simple Preloader Using the ProgressBar Control
 *
 * @author hassan
 */
public class TeleMart_Preloader extends Preloader {

    ProgressBar bar;
    Stage stage;

    private Scene createPreloaderScene() {
        bar = new ProgressBar();
        BorderPane p = new BorderPane();
        p.setCenter(bar);
        return new Scene(p, 300, 150);        
    }

    @Override
    public void start(Stage stage) throws Exception {
        this.stage = stage;
        stage.setScene(createPreloaderScene());        
        stage.show();
    }

    @Override
    public void handleStateChangeNotification(StateChangeNotification scn) {
        if (scn.getType() == StateChangeNotification.Type.BEFORE_START) {
            stage.hide();
        }
    }

    @Override
    public void handleProgressNotification(ProgressNotification pn) {
        bar.setProgress(pn.getProgress());
    }    

}

com.hassanalthaf.telemart.Main.java:

/*
 * Program developed by Hassan Althaf.
 * Copyright © 2015, Hassan Althaf.
 * Website: http://hassanalthaf.com
 */
package com.hassanalthaf.telemart;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

/**
 *
 * @author hassan
 */
public class Main extends Application {

    public static final String APPLICATION_TITLE = "TeleMart - ERP System";

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("views/MainView.fxml"));

        Scene scene = new Scene(root);

        stage.setScene(scene);
        stage.setResizable(false);
        stage.setTitle(Main.APPLICATION_TITLE);
        stage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

}

com.hassanalthaf.telemart.views.Dashboard.fxml:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.shape.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" fx:id="dashboard" prefHeight="400.0" prefWidth="600.0" stylesheets="@css/dashboard.css" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.hassanalthaf.telemart.viewmodels.DashboardViewModel">
   <children>
      <MenuBar maxWidth="600.0" minWidth="600.0" prefWidth="600.0">
        <menus>
          <Menu mnemonicParsing="false" text="File">
            <items>
              <MenuItem fx:id="homeMenuItem" mnemonicParsing="false" onAction="#menuItemClick" text="Home" />
                  <MenuItem fx:id="anotherPageMenuItem" mnemonicParsing="false" onAction="#menuItemClick" text="Another Page" />
                  <MenuItem fx:id="differentPageMenuItem" mnemonicParsing="false" onAction="#menuItemClick" text="Different Page" />
            </items>
          </Menu>
        </menus>
      </MenuBar>
      <AnchorPane fx:id="differentPage" layoutY="29.0" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" opacity="0.0" prefHeight="371.0" prefWidth="600.0">
         <children>
            <TextArea layoutX="155.0" layoutY="62.0" prefHeight="200.0" prefWidth="200.0" promptText="Page three" />
         </children>
      </AnchorPane>
      <AnchorPane fx:id="anotherPage" layoutY="29.0" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" opacity="0.0" prefHeight="371.0" prefWidth="600.0">
         <children>
            <TextField layoutX="180.0" layoutY="77.0" promptText="Page Two" />
         </children>
      </AnchorPane>
      <AnchorPane fx:id="home" layoutY="29.0" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="371.0" prefWidth="600.0">
         <children>
            <TextField layoutX="133.0" layoutY="150.0" text="First Page" />
         </children>
      </AnchorPane>
   </children>
</AnchorPane>

com.hassanalthaf.telemart.views.MainView.fxml:

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" fx:id="mainWindow" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="350.0" prefWidth="600.0" stylesheets="@css/style.css" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.hassanalthaf.telemart.viewmodels.MainViewModel">
   <children>
      <Label layoutX="222.0" layoutY="35.0" styleClass="title" text="TeleMart" />
      <TextField layoutX="380.0" layoutY="160.0" onKeyPressed="#loginEnter" promptText="Username">
         <styleClass>
            <String fx:value="login-field" />
            <String fx:value="login-field" />
         </styleClass>
      </TextField>
      <PasswordField layoutX="380.0" layoutY="208.0" onKeyPressed="#loginEnter" promptText="Password" styleClass="login-field" />
      <Button layoutX="495.0" layoutY="256.0" mnemonicParsing="false" onMouseClicked="#loginClick" text="Login" />
      <Label layoutX="45.0" layoutY="113.0" styleClass="content" text="Welcome to TeleMart's Enterprise&#10;Resource Planning System.&#10;Please enter your login credentials&#10;on the right so that we could verify&#10;your identity. Also, please do not&#10;share your login credentials with&#10;anyone or use another person's&#10;login credentials." textAlignment="CENTER" wrapText="true" />
      <Label layoutX="220.0" layoutY="309.0" styleClass="content" text="© 2015, Hassan Althaf." />
   </children>
</AnchorPane>

com.hassanalthaf.telemart.views.css.style.css:

/*
Program developed by Hassan Althaf.
Copyright © 2015, Hassan Althaf.
Website: http://hassanalthaf.com
*/
/* 
    Created on : Dec 19, 2015, 6:09:52 PM
    Author     : hassan
*/

@font-face {
    font-family: 'Lato-Regular';
    src: url('../fonts/Lato-Regular.ttf');
}

@font-face {
    font-family: 'Lato-Hairline';
    src: url('../fonts/Lato-Hairline.ttf');
}

.root {
    -fx-background-color: #2C3E50;
}

.title {
    -fx-font-family: 'Lato-Hairline';
    -fx-font-size: 30pt;
    -fx-text-fill: #FFFFFF;
}

.login-field {
    -fx-background-color: #FFFFFF;
    -fx-border-radius: 5pt;
    -fx-padding: 10px;
    -fx-border-width: 1pt;
    -fx-border-style: solid;
    -fx-border-color: #202D3A;
    -fx-background-insets: 2, 0, 0;
    -fx-font-family: 'Lato-Regular';
}

.button {
    -fx-background-color: #3498DB;
    -fx-text-fill: #FFFFFF;
    -fx-font-size: 11pt;
    -fx-padding: 8px;
    -fx-border-radius: 10pt;
}

.button:hover {
    -fx-background-color: #51A7E0;
}

.content {
    -fx-font-family: 'Lato-Regular';
    -fx-font-size: 11pt;
    -fx-text-fill: #FFFFFF;
}

com.hassanalthaf.telemart.views.css.dashboard.css:

/*
Program developed by Hassan Althaf.
Copyright © 2015, Hassan Althaf.
Website: http://hassanalthaf.com
*/
/* 
    Created on : Dec 19, 2015, 11:29:50 PM
    Author     : hassan
*/
@font-face {
    font-family: 'Lato-Regular';
    src: url('../fonts/Lato-Regular.ttf');
}

.menu-bar {
    -fx-background-color: #3498DB;
}

.menu:hover {
    -fx-background-color: #51A7E0;
}

.menu:showing {
    -fx-background-color: #2487C9;
}

.menu .label {
    -fx-text-fill: #FFFFFF;
    -fx-font-family: 'Lato-Regular';
    -fx-font-size: 10pt;
}

.menu-item {
    -fx-background-color: #FFFFFF;
}

.menu-item:hover {
    -fx-background-color: #51A7E0;
}

.menu-item .label {
    -fx-text-fill: #333333;
    -fx-font-family: 'Lato-Regular';
    -fx-font-size: 10pt;
}

.menu-item:hover .label {
    -fx-text-fill: #FFFFFF;
}

com.hassanalthaf.telemart.viewmodels.MainViewModel.java:

/*
 * Program developed by Hassan Althaf.
 * Copyright © 2015, Hassan Althaf.
 * Website: http://hassanalthaf.com
 */
package com.hassanalthaf.telemart.viewmodels;

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.input.MouseEvent;

/**
 *
 * @author hassan
 */
public class MainViewModel implements Initializable {

    @FXML
    private Parent mainWindow;

    @FXML
    private void loginClick(MouseEvent event) {
        try {
            this.openDashboard();
        } catch (IOException exception) {

        }
    }

    @FXML
    private void loginEnter(KeyEvent event) {
        if (event.getCode() == KeyCode.ENTER) {
            try {
                this.openDashboard();
            } catch (IOException exception) {
                exception.printStackTrace();
            }
        }
    }

    private void openDashboard() throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/com/hassanalthaf/telemart/views/Dashboard.fxml"));
        Parent dashboard = fxmlLoader.load();
        DashboardViewModel dashboardViewModel = fxmlLoader.getController();
        dashboardViewModel.show(this.mainWindow);
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }

}

com.hassanalthaf.telemart.viewmodels.DashboardViewModel.java:

/*
 * Program developed by Hassan Althaf.
 * Copyright © 2015, Hassan Althaf.
 * Website: http://hassanalthaf.com
 */
package com.hassanalthaf.telemart.viewmodels;

import com.hassanalthaf.telemart.Main;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;

/**
 * FXML Controller class
 *
 * @author hassan
 */
public class DashboardViewModel implements Initializable {

    @FXML
    private Parent dashboard;

    @FXML
    private AnchorPane home;

    @FXML
    private AnchorPane anotherPage;

    @FXML
    private AnchorPane differentPage;

    private AnchorPane currentPage;

    private void changePage(AnchorPane page) {
        this.currentPage.setOpacity(0);
        this.currentPage = page;
        this.currentPage.toFront();
        this.currentPage.setOpacity(1);
    }

    public void menuItemClick(ActionEvent event) {
        Object source = (MenuItem)event.getSource();
        MenuItem clickedItem;

        if(source instanceof MenuItem) {
            clickedItem = (MenuItem)source;
        } else {
            return;
        }

        String id = clickedItem.getId();

        switch (id) {
            case "homeMenuItem":
                this.changePage(this.home);
                break;
            case "anotherPageMenuItem":
                this.changePage(this.anotherPage);
                break;
            case "differentPageMenuItem":
                this.changePage(this.differentPage);
                break;
            default:
                this.changePage(this.home);
                break;
        }
    }

    public void show(Parent main) {
        Scene scene = new Scene(this.dashboard);

        Stage stage = new Stage();
        stage.setScene(scene);
        stage.setTitle(Main.APPLICATION_TITLE);
        stage.setResizable(false);
        stage.show();

        Stage mainStage = (Stage)main.getScene().getWindow();
        mainStage.close();
    }

    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
        this.currentPage = this.home;
    }    

}

The entire source code with all the assets can be found here on GitHub.