ComboBoxDemo.java

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.image.ImageView;
import javafx.scene.layout.BorderPane;

public class ComboBoxDemo extends Application {
  // Declare an array of Strings for flag titles
  private String[] flagTitles = {"Canada", "China", "Denmark", 
    "France", "Germany", "India", "Norway", "United Kingdom",
    "United States of America"};

  // Declare an ImageView array for the national flags of 9 countries
  private ImageView[] flagImage = {new ImageView("image/ca.gif"),
    new ImageView("image/china.gif"), 
    new ImageView("image/denmark.gif"), 
    new ImageView("image/fr.gif"), 
    new ImageView("image/germany.gif"),
    new ImageView("image/india.gif"), 
    new ImageView("image/norway.gif"),
    new ImageView("image/uk.gif"), new ImageView("image/us.gif")};

  // Declare an array of strings for flag descriptions
  private String[] flagDescription = new String[9];

  // Declare and create a description pane
  private DescriptionPane descriptionPane = new DescriptionPane();

  // Create a combo box for selecting countries
  private ComboBox<String> cbo = new ComboBox<>(); // flagTitles

  @Override // Override the start method in the Application class
  public void start(Stage primaryStage) {
    // Set text description
    flagDescription[0] = "The Canadian national flag ...";
    flagDescription[1] = "Description for China ... ";
    flagDescription[2] = "Description for Denmark ... ";
    flagDescription[3] = "Description for France ... ";
    flagDescription[4] = "Description for Germany ... ";
    flagDescription[5] = "Description for India ... ";
    flagDescription[6] = "Description for Norway ... ";
    flagDescription[7] = "Description for UK ... ";
    flagDescription[8] = "Description for US ... ";

    // Set the first country (Canada) for display
    setDisplay(0);

    // Add combo box and description pane to the border pane
    BorderPane pane = new BorderPane();
      
    BorderPane paneForComboBox = new BorderPane();
    paneForComboBox.setLeft(new Label("Select a country: "));
    paneForComboBox.setCenter(cbo);
    pane.setTop(paneForComboBox);
    cbo.setPrefWidth(400);
    cbo.setValue("Canada");
    
    ObservableList<String> items = 
      FXCollections.observableArrayList(flagTitles);
    cbo.getItems().addAll(items); 
    pane.setCenter(descriptionPane);
    
    // Display the selected country
    cbo.setOnAction(e -> setDisplay(items.indexOf(cbo.getValue())));
    
    // Create a scene and place it in the stage
    Scene scene = new Scene(pane, 450, 170);
    primaryStage.setTitle("ComboBoxDemo"); // Set the stage title
    primaryStage.setScene(scene); // Place the scene in the stage
    primaryStage.show(); // Display the stage
  }

  /** Set display information on the description pane */
  public void setDisplay(int index) {
    descriptionPane.setTitle(flagTitles[index]);
    descriptionPane.setImageView(flagImage[index]);
    descriptionPane.setDescription(flagDescription[index]);
  }

  /**
   * The main method is only needed for the IDE with limited
   * JavaFX support. Not needed for running from the command line.
   */
  public static void main(String[] args) {
    launch(args);
  }
}