package test;

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class RestrictedCombo extends Application {
    @Override public void start(Stage stage) {
        final StackPane root = new StackPane();

        final ObservableList<String> items =
                FXCollections.observableArrayList("Good value", "Bad value");

        final ComboBox<String> combo = new ComboBox<>(items);
        combo.getSelectionModel().select(0);

        combo.getSelectionModel().selectedIndexProperty().addListener(
                new ChangeListener<Number>() {
            @Override public void changed(ObservableValue<? extends Number> ov,
                    Number oldIdx, Number newIdx) {
                if (newIdx != 0) {
                    combo.getSelectionModel().select(0);
                }
            }
        });

        root.getChildren().add(combo);
        final Scene scene = new Scene(root, 400, 400);

        stage.setTitle("Restricted combo box");
        stage.setScene(scene);
        stage.show();
    }

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