(Control a clock) Modify Listing 14.21, ClockPane.java, to add the animation into this class and add two methods start() and stop() to start and stop the clock

import javafx.animation.Animation;
import javafx.animation.Timeline;
import javafx.animation.KeyFrame;
import java.util.Calendar;
import java.util.GregorianCalendar;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.scene.text.Text;
import javafx.util.Duration;

public class ClockPane extends Pane {
	private int hour;
	private int minute;
	private int second;
	private Timeline animation;

	// Clock pane's width and height
	private double w = 250, h = 250;

	/** Construct a default clock with the current time */
	public ClockPane() {
		setCurrentTime();
		animation = new Timeline(
			new KeyFrame(Duration.millis(1000), e -> moveClock()));
		animation.setCycleCount(Timeline.INDEFINITE);
		animation.play();
	}

	/** Construct a click with specified hour, minute, and second */
	public ClockPane(int hour, int minute, int second) {
		this.hour = hour;
		this.minute = minute;
		this.second = second;
		paintClock();
		animation = new Timeline(
			new KeyFrame(Duration.millis(1000), e -> moveClock()));
		animation.setCycleCount(Timeline.INDEFINITE);
		animation.play();
	}

	/** Return hour */
	public int getHour() {
		return hour;
	}

	/** Set a new hour */
	public void setHour(int hour) {
		this.hour = hour;
		paintClock();
	}

	/** Return minute */
	public int getMinute() {
		return minute;
	}

	/** Set a new minute */
	public void setMinute(int minute) {
		this.minute = minute;
		paintClock();
	}

	/** Return second */
	public int getSecond() {
		return second;
	}

	/** Set a new second */
	public void setSecond(int second) {
		this.second = second;
		paintClock();
	}

	/** Return clock pane's width */
	public double getW() {
		return w;
	}

	/** Set clock pane's width */
	public void getW(double w) {
		this.w = w;
		paintClock();
	}

	/** Return clock pane's height */
	public double getH() {
		return h;
	}

	/** Set clock pane's heigt */
	public void setH(double h) {
		this.h = h;
		paintClock();
	}

	/* Set the current time for the clock */
	public void setCurrentTime() {
		// Construct a Calendar for the current date and time
		Calendar calendar = new GregorianCalendar();

		// Set current hour, minute and second
		this.hour = calendar.get(Calendar.HOUR_OF_DAY);
		this.minute = calendar.get(Calendar.MINUTE);
		this.second = calendar.get(Calendar.SECOND);
		paintClock(); // Repaint the clock
	}
	
	/** Paint the clock */
	protected void paintClock() {
		// Initialize clock parameters
		double clockRadius = Math.min(w, h) * 0.8 * 0.5;
		double centerX = w / 2;
		double centerY = h / 2;

		// Draw circle
		Circle circle = new Circle(centerX, centerY, clockRadius);
		circle.setFill(Color.WHITE);
		circle.setStroke(Color.BLACK);
		Text t1 = new Text(centerX - 5, centerY - clockRadius + 12, "12");
		Text t2 = new Text(centerX - clockRadius + 3, centerY + 5, "9");
		Text t3 = new Text(centerX + clockRadius - 10, centerY + 3, "3");
		Text t4 = new Text(centerX - 3, centerY + clockRadius - 3, "6");

		// Draw second hand
		double sLength = clockRadius * 0.8;
		double secondX = centerX + sLength *
			Math.sin(second * (2 * Math.PI / 60));
		double secondY = centerY - sLength *
			Math.cos(second * (2 * Math.PI / 60));
		Line sLine = new Line(centerX, centerY, secondX, secondY);
		sLine.setStroke(Color.RED);

		// Draw minute hand
		double mLength = clockRadius * 0.65;
		double xMinute = centerX + mLength *
			Math.sin(minute * (2 * Math.PI / 60));
		double minuteY = centerY - mLength *
			Math.cos(minute * (2 * Math.PI / 60));
		Line mLine = new Line(centerX, centerY, xMinute, minuteY);
		mLine.setStroke(Color.BLUE);

		// Draw hour hand 
		double hLength = clockRadius * 0.5;
		double hourX = centerX + hLength *
			Math.sin((hour % 12 + minute / 60.0) * (2 * Math.PI / 12));
		double hourY = centerY - hLength * 
			Math.cos((hour % 12 + minute / 60.0) * (2 * Math.PI / 12));
		Line hLine = new Line(centerX, centerY, hourX, hourY);
		hLine.setStroke(Color.GREEN);

		getChildren().clear();
		getChildren().addAll(circle, t1, t2, t3, t4, sLine, mLine, hLine);
	}

	/* Animate the clock */
	protected void moveClock() {
		if (minute == 60) {
			hour += 1; 
		}	
		if (second == 60) {
			minute += 1;
		}
		second = (second < 60 ? second + 1 : 1);
		paintClock();	
	}

	public void play() {
		animation.play();
	}

	public void pause() {
		animation.pause();
	}
}

Exercise_15_32.java 

/*********************************************************************************
* (Control a clock) Modify Listing 14.21, ClockPane.java, to add the animation   *
* into this class and add two methods start() and stop() to start and stop the   *
* clock. Write a program that lets the user control the clock with the Start and *
* Stop buttons, as shown in Figure 15.36a.                                       *
*********************************************************************************/
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.scene.layout.BorderPane;
import javafx.geometry.Pos;
import javafx.stage.Stage;

public class Exercise_15_32 extends Application {
	@Override // Override the start method in the Application class
	public void start(Stage primaryStage) {
		// Create a clock pane
		ClockPane clock = new ClockPane();

		// Create a hBox and set it porperties
		HBox hBox = new HBox(5);
		hBox.setAlignment(Pos.CENTER);

		// Create two buttons
		Button btStop = new Button("Stop");
		Button btStart = new Button("Start");

		// Create and register handler
		btStop.setOnAction(e -> clock.pause());
		btStart.setOnAction(e -> clock.play());

		// Place buttons in hBox
		hBox.getChildren().addAll(btStop, btStart);

		// Create a border pane and place the nodes in to it
		BorderPane borderPane = new BorderPane();
		borderPane.setCenter(clock);
		borderPane.setBottom(hBox);

		// Create a scene and place it in the stage
		Scene scene = new Scene(borderPane, 250, 270);
		primaryStage.setTitle("Exercise_15_32"); // Set the stage title
		primaryStage.setScene(scene); // Place the scene in the stage
		primaryStage.show(); // Display the stage
	}
}