JavaFX: ChoiceBox demo.

Main.java

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ChoiceBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Main extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {

        ObservableList<String> datos = FXCollections.observableArrayList("Simple", "Doble", "Triple");

        ChoiceBox choiceBox = new ChoiceBox(datos);

        // Solo si quieren que pase algo cuando se selecciona
        choiceBox.getSelectionModel().selectedItemProperty().addListener(new ChangeListener() {
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) {
                String seleccion = (String) newValue;
                System.out.println("Seleccionaste: " + seleccion);
            }
        });

        Button aceptarButton = new Button("Aceptar");
        aceptarButton.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                // Para obtener lo seleccionado
                String seleccion = (String) choiceBox.getSelectionModel().getSelectedItem();
                System.out.println("Seleccionaste: " + seleccion);
            }
        });

        VBox vBox = new VBox();
        vBox.getChildren().addAll(choiceBox, aceptarButton);
        vBox.setPadding(new Insets(20));
        vBox.setSpacing(20);

        Scene scene = new Scene(vBox, 200, 120);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}