JavaFX の ChoiceBox から選択したアイテムを取得する

ChoiceBox.getSelectionModel().selectedIndexProperty()

package delftstack;

import javafx.application.Application;
import javafx.beans.value.*;
import javafx.collections.*;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.stage.Stage;
public class Choice_Box extends Application {
  public void start(Stage Choice_Box_Stage) {
    // title for the stage
    Choice_Box_Stage.setTitle("ChoiceBox");

    // button to show
    Button Show_Button = new Button("Show Choice");

    // tile pane
    TilePane Title_Pane = new TilePane();

    // labels
    Label Label1 = new Label("This is a choice box, Please select your choice");
    Label Label2 = new Label("No Choice selected");

    // Choices array
    String Choice_Array[] = {
        "Delftstack 1", "Delftstack 2", "Delftstack 3", "Delftstack 4", "Delftstack 5"};

    // choiceBox
    ChoiceBox DemoChoiceBox = new ChoiceBox(FXCollections.observableArrayList(Choice_Array));

    // adding a listener
    DemoChoiceBox.getSelectionModel().selectedIndexProperty().addListener(
        new ChangeListener<Number>() {
          // if items of the list are changed
          public void changed(ObservableValue ov, Number value, Number new_value) {
            // text for the label to the selected item
            Label2.setText(Choice_Array[new_value.intValue()] + " is Selected");
          }
        });

    // ChoiceBox
    Title_Pane.getChildren().add(Label1);
    Title_Pane.getChildren().add(DemoChoiceBox);
    Title_Pane.getChildren().add(Label2);

    Scene sc = new Scene(Title_Pane, 400, 200);

    // Setting the scene
    Choice_Box_Stage.setScene(sc);

    Choice_Box_Stage.show();
  }

  public static void main(String args[]) {
    // launching the application
    launch(args);
  }
}