JavaFX Pane extend to create traffic light

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Rectangle;
import javafx.scene.shape.Shape;
import javafx.stage.Stage;

public class Main extends Application {
   @Override//from  www  . ja v a2  s  . co m
   public void start(Stage primaryStage) throws Exception {
      Pane pane = new TrafficLightPane(300, 300);
      primaryStage.setScene(new Scene(pane));
      primaryStage.setTitle("Traffic Light");
      primaryStage.show();
   }

}

class TrafficLightPane extends Pane {

   double w;
   double h;

   public TrafficLightPane(double width, double height) {

      w = width;
      h = height;
      setPrefWidth(w);
      setPrefHeight(h);

      Rectangle rec = new Rectangle(w / 3, h / 6, w / 3, h / 1.5);
      rec.setFill(Color.TRANSPARENT);
      rec.setStroke(Color.BLACK);
      getChildren().add(rec);

      // Radio buttons names
      String[] colorString = { "Red", "Yellow", "Green" };

      ToggleGroup group = new ToggleGroup();

      Circle[] circles = new Circle[3];
      Color[] colors = new Color[] { Color.RED, Color.YELLOW, Color.GREEN };
      double[] circleY = new double[] { 0.3, 0.5, 0.7 };
      RadioButton[] rbColors = new RadioButton[circles.length];

      for (int i = 0; i < circles.length; i++) {
         circles[i] = new Circle(w / 2, h * circleY[i], w * 0.09);
         circles[i].setFill(Color.TRANSPARENT);
         circles[i].setStroke(Color.BLACK);
         rbColors[i] = new RadioButton(colorString[i]);

         final int index = i;
         rbColors[i].setOnAction(e -> {
            resetColors(circles);
            circles[index].setFill(colors[index]);
         });
         rbColors[i].setToggleGroup(group);
      }

      HBox radioButtonPane = new HBox(10);
      radioButtonPane.getChildren().addAll(rbColors);
      radioButtonPane.setAlignment(Pos.CENTER);
      radioButtonPane.setLayoutX(w * 0.2);
      radioButtonPane.setLayoutY(h - 30);

      getChildren().addAll(circles);
      getChildren().addAll(radioButtonPane);
   }

   private void resetColors(Shape[] shapes) {
      for (Shape s : shapes) {
         s.setFill(Color.TRANSPARENT);
      }
   }
}