import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Test extends Application {

	@Override
	public void start(Stage primaryStage) {
		var comboBox = new ComboBox<String>();
		comboBox.setEditable(true);
		comboBox.valueProperty().addListener((obs, ov, nv) -> {
			System.out.printf("ComboBox.onValueChanged: %s%n", nv);
		});

		var defaultButton = new Button("Default button");
		defaultButton.setDefaultButton(true);
		defaultButton.setOnAction(e -> {
			var value = comboBox.getValue();
			System.out.printf("Button.onAction: %s%n", value);
		});

		primaryStage.setScene(new Scene(new VBox(comboBox, defaultButton)));
		primaryStage.show();
	}

	public static void main(String[] args) {
		Application.launch(Test.class, args);
	}
}