(Control a group of fans) Write a program that displays three fans in a group, with control buttons to start and stop all of them, as shown in Figure 16.44

/*********************************************************************************
* (Control a group of fans) Write a program that displays three fans in a group, *
* with control buttons to start and stop all of them, as shown in Figure 16.44.  *
*********************************************************************************/
import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.collections.ObservableList;

public class Exercise_16_19 extends Application {
	// Create two buttons
	protected Button btStartAll = new Button("Start All");
	protected Button btStopAll = new Button("Stop All");

	@Override // Override the start method in the appliction class
	public void start(Stage primaryStage) {
		// Create a two hboxs
		HBox paneForFans = new HBox(5);
		paneForFans.setAlignment(Pos.CENTER);
		paneForFans.getChildren().addAll(getFan(), getFan(), getFan());

		HBox paneForButtons = new HBox(5);
		paneForButtons.setAlignment(Pos.CENTER);
		paneForButtons.getChildren().addAll(btStartAll, btStopAll);

		// Create a pane
		BorderPane pane = new BorderPane();
		pane.setCenter(paneForFans);
		pane.setBottom(paneForButtons);

		// Create a list of fan panes
		ObservableList<Node> list = paneForFans.getChildren();

		// Create and register handlers
		btStopAll.setOnAction(e -> {
			for (Node x : list) {
				((FanPane)((BorderPane)x).getCenter()).pause();
			}
		});

		btStartAll.setOnAction(e -> {
			for (Node x : list) {
				((FanPane)((BorderPane)x).getCenter()).play();
			}
		});

		// Create a scene and place it in the stage
		Scene scene = new Scene(pane, 610, 200);
		primaryStage.setTitle("Exercise_16_19"); // Set the stage title
		primaryStage.setScene(scene); // Place the scene in the stage
		primaryStage.show(); // Display the stage
	}

	/** Returns a fan pane */
	public BorderPane getFan() {
		// Create three buttons
		Button btPause = new Button("Pause");
		Button btResume = new Button("Resume");
		Button btReverse = new Button("Reverse");

		// Place buttons in a hbox
		HBox paneForButtons = new HBox(5);
		paneForButtons.getChildren().addAll(btPause, btResume, btReverse);

		// Create a fan pane
		FanPane fan = new FanPane();

		// Create a slider and set its properties
		Slider slider = new Slider();
		slider.setMax(5);
		fan.rateProperty().bind(slider.valueProperty());

		// Create a border pane
		BorderPane pane = new BorderPane();
		pane.setStyle("-fx-border-color: black");
		pane.setTop(paneForButtons);
		pane.setCenter(fan);
		pane.setBottom(slider);

		// Create and register the handlers
		btPause.setOnAction(e -> {
			fan.pause();
		});

		btResume.setOnAction(e -> {
			fan.play();
		});

		btReverse.setOnAction(e -> {
			fan.reverse();
		});

		return pane;
	}
}

FanPane.java

import javafx.collections.ObservableList;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.paint.Color;
import javafx.scene.Node;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.animation.Timeline;
import javafx.animation.KeyFrame;
import javafx.util.Duration;
import javafx.geometry.Insets;
import javafx.beans.property.DoubleProperty;

public  class FanPane extends Pane {
	private Circle circle = new Circle();
	private double startAngle = 15; // Start angle of arcs
	private Timeline fan; // animation
	private Pane paneForBlades = new Pane(); // Create four arcs
	private Arc arc;

	/**  Construct a FanPane */
	public FanPane() {
		setPadding(new Insets(10, 10, 10, 10));
		circle.setStroke(Color.BLACK);
		circle.setFill(Color.WHITE);
		circle.centerXProperty().bind(widthProperty().divide(2));
		circle.centerYProperty().bind(heightProperty().divide(2));
		circle.radiusProperty().bind((heightProperty().divide(2)).multiply(.90));
		getBlades();
		getChildren().addAll(circle, paneForBlades);
		fan = new Timeline(
			new KeyFrame(Duration.millis(50), e -> spinFan()));
		fan.setCycleCount(Timeline.INDEFINITE);
		fan.play(); // Start animation
	}

	/** Animate fan blades */
	protected void spinFan() {
		ObservableList<Node> list = paneForBlades.getChildren();
		for (Node n: list) {
			((Arc)n).setStartAngle(((Arc)n).getStartAngle() + startAngle);
		}
	}

	/** Pause animation */
	public void pause() {
		fan.pause();
	}

	/** Resume animation */
	public void play() {
		fan.play();
	}

	/** Reverse the direction of fan spin */
	public void reverse() {
		startAngle *= -1;
	}

	// return rateProperty
	public DoubleProperty rateProperty() {
		return fan.rateProperty();
	} 

	/** Add four arcs to a pane and place them in a stack pane */
	private void getBlades() {
		double angle = 0;
		for (int i = 0; i < 4; i++) {
			arc = new Arc(); 
			arc.centerXProperty().bind(widthProperty().divide(2));
			arc.centerYProperty().bind(heightProperty().divide(2));
			arc.radiusXProperty().bind(circle.radiusProperty().multiply(.90));
			arc.radiusYProperty().bind(circle.radiusProperty().multiply(.90));
			arc.setStartAngle(angle + 90);
			arc.setLength(50);
			arc.setFill(Color.BLACK);
			arc.setType(ArcType.ROUND);
			paneForBlades.getChildren().add(arc);
			angle += 90;
		}
	}
}