JavaFX fxml combo box selection demonstration app

fruitcombo.css

/** fruitcombo.css
    place in same directory as FruitComboApplication.java 
    ensure build system copies the css file to the build output path */

.layout { 
  -fx-background-color: cornsilk;
}

#selected-fruit-frame {
  -fx-border-color: burlywood;
  -fx-border-width: 5;
  -fx-background-color: white;
}

.bold-label {
  -fx-font-weight: bold;  
}

fruitcombo.fxml

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

<!-- fruitcombo.fxml 
     place in same directory as FruitComboApplication.java 
     ensure build system copies the fxml file to the build output path -->
     
<?import java.lang.*?>
<?import java.net.*?>
<?import java.util.*?>
<?import javafx.collections.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.paint.*?>
<?scenebuilder-stylesheet fruitcombo.css?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="205.0" prefWidth="168.0" styleClass="layout" xmlns:fx="http://javafx.com/fxml" fx:controller="fruit.FruitComboController">
  <children>
    <ComboBox fx:id="fruitCombo" layoutX="15.0" layoutY="33.0" prefWidth="90.0" promptText="choose">
      <items>
        <FXCollections fx:factory="observableArrayList">
          <String fx:value="Apple" />
          <String fx:value="Orange" />
          <String fx:value="Pear" />
        </FXCollections>
      </items>
    </ComboBox>
    <Label id="fruitSelectorLabel" layoutX="15.0" layoutY="10.0" styleClass="bold-label" text="Fruit Selector" />
    <VBox alignment="TOP_CENTER" layoutX="14.0" layoutY="62.0" prefHeight="134.0" prefWidth="140.0" spacing="8.0">
      <children>
        <StackPane id="selected-fruit-frame" minHeight="100.0" minWidth="118.0" prefHeight="108.0" prefWidth="140.0">
          <children>
            <ImageView fx:id="orangeImage" fitHeight="91.99999237060547" fitWidth="122.66666035739114" pickOnBounds="true" preserveRatio="true" visible="false">
              <image>
                <Image url="http://pngimg.com/upload/orange_PNG803.png" preserveRatio="false" smooth="false" />
              </image>
            </ImageView>
            <ImageView fx:id="pearImage" fitHeight="93.0" fitWidth="124.0" pickOnBounds="true" preserveRatio="true" visible="false">
              <image>
                <Image url="http://thedeliciousrevolution.com/wp-content/uploads/2008/08/Pears.png" preserveRatio="false" smooth="false" />
              </image>
            </ImageView>
            <ImageView fx:id="appleImage" fitHeight="93.0" fitWidth="124.0" pickOnBounds="true" preserveRatio="true" visible="false">
              <image>
                <Image url="http://uhallnyu.files.wordpress.com/2011/11/green-apple.jpg" preserveRatio="false" smooth="false" />
              </image>
            </ImageView>
          </children>
        </StackPane>
        <Label fx:id="selectedFruit" textAlignment="CENTER" />
      </children>
    </VBox>
  </children>
  <stylesheets>
    <URL value="@fruitcombo.css" />
  </stylesheets>
</AnchorPane>

FruitComboApplication.java

package fruit;

import java.io.IOException;
import java.net.URL;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;

/** Main application class for fruit combo fxml demo application */
public class FruitComboApplication extends Application {
  public static void main(String[] args) { launch(args); }
  @Override public void start(Stage stage) throws IOException {
    stage.setTitle("Choices");
    stage.getIcons().add(new Image("http://files.softicons.com/download/application-icons/pixelophilia-icons-by-omercetin/png/32/apple-green.png"));
    AnchorPane layout = FXMLLoader.load(
      new URL(FruitComboApplication.class.getResource("fruitcombo.fxml").toExternalForm())
    );
    stage.setScene(new Scene(layout));
    stage.show();
  }
}

FruitComboController.java

package fruit;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.image.ImageView;

/** JavaFX fxml controller for fruit combo fxml demo application. */
public class FruitComboController implements Initializable {

  @FXML //  fx:id="appleImage"
  private ImageView appleImage; // Value injected by FXMLLoader

  @FXML //  fx:id="fruitCombo"
  private ComboBox<String> fruitCombo; // Value injected by FXMLLoader

  @FXML //  fx:id="orangeImage"
  private ImageView orangeImage; // Value injected by FXMLLoader

  @FXML //  fx:id="pearImage"
  private ImageView pearImage; // Value injected by FXMLLoader

  @FXML //  fx:id="selectedFruit"
  private Label selectedFruit; // Value injected by FXMLLoader

  @Override // This method is called by the FXMLLoader when initialization is complete
  public void initialize(URL fxmlFileLocation, ResourceBundle resources) {
    assert appleImage != null : "fx:id=\"appleImage\" was not injected: check your FXML file 'fruitcombo.fxml'.";
    assert fruitCombo != null : "fx:id=\"fruitCombo\" was not injected: check your FXML file 'fruitcombo.fxml'.";
    assert orangeImage != null : "fx:id=\"orangeImage\" was not injected: check your FXML file 'fruitcombo.fxml'.";
    assert pearImage != null : "fx:id=\"pearImage\" was not injected: check your FXML file 'fruitcombo.fxml'.";
    assert selectedFruit != null : "fx:id=\"selectedFruit\" was not injected: check your FXML file 'fruitcombo.fxml'.";

    // bind the selected fruit label to the selected fruit in the combo box.
    selectedFruit.textProperty().bind(fruitCombo.getSelectionModel().selectedItemProperty());

    // listen for changes to the fruit combo box selection and update the displayed fruit image accordingly.
    fruitCombo.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<String>() {
      @Override public void changed(ObservableValue<? extends String> selected, String oldFruit, String newFruit) {
        if (oldFruit != null) {
          switch(oldFruit) {
            case "Apple":  appleImage.setVisible(false);  break;
            case "Orange": orangeImage.setVisible(false); break;
            case "Pear":   pearImage.setVisible(false);   break;
          }
        }
        if (newFruit != null) {
          switch(newFruit) {
            case "Apple":  appleImage.setVisible(true);   break;
            case "Orange": orangeImage.setVisible(true);  break; 
            case "Pear":   pearImage.setVisible(true);    break;
          }
        }  
      }
    });
  }
}

thank you for the code