Consider the animation code from the end of Chapter 4. Modify the ShapeIcon class so that it aggregates a collection of objects implementing the MovableShape interface and its paintIcon() method takes care of painting all the given MovableShape objects. Modify the animation program (AnimationTester. main) to display 5 cars moving horizontally, each starting from a different vertical coordinate, so that the car with index i moves twice as fast as the car with index i - 1.

import java.awt.*;

import java.util.*;

import javax.swing.*;

/**

An icon that contains a moveable shape.

*/

public class ShapeIcon implements Icon

{

private int width;

private int height;

private MoveableShape shape;

private ArrayList <MoveableShape> cars;

public ShapeIcon(MoveableShape shape,

int width, int height)

{

this.shape = shape;

this.width = width;

this.height = height;

cars = new ArrayList<MoveableShape>();

}

public int getIconWidth()

{

return width;

}

public int getIconHeight()

{

return height;

}

public void paintIcon(Component c, Graphics g, int x, int y)

{

Graphics2D g2 = (Graphics2D) g;

shape.draw(g2);

}

}

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

/**

This program implements an animation that moves

a car shape.

*/

public class AnimationTester

{

private static final int ICON_WIDTH = 400;

private static final int ICON_HEIGHT = 100;

private static final int CAR_WIDTH = 100;

public static void main(String[] args)

{

JFrame frame = new JFrame();

final MoveableShape shape

= new CarShape(0, 0, CAR_WIDTH);

ShapeIcon icon = new ShapeIcon(shape,

ICON_WIDTH, ICON_HEIGHT);

final JLabel label = new JLabel(icon);

frame.setLayout(new FlowLayout());

frame.add(label);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.pack();

frame.setVisible(true);

final int DELAY = 10; //100

// Milliseconds between timer ticks

Timer t = new Timer(DELAY, new

ActionListener()

{

public void actionPerformed(ActionEvent event)

{

shape.translate(1, 0);

label.repaint();

}

});

t.start();

}

}

import java.awt.*;

import java.awt.geom.*;

import java.util.*;

/**

A car that can be moved around.

*/

public class CarShape implements MoveableShape

{

private int x;

private int y;

private int width;

/**

Constructs a car item.

@param x the left of the bounding rectangle

@param y the top of the bounding rectangle

@param width the width of the bounding rectangle

*/

public CarShape(int x, int y, int width)

{

this.x = x;

this.y = y;

this.width = width;

}

public void translate(int dx, int dy)

{

// x += dx;

// y += dy;

if (x <= 400)

x += dx;

else

x = 0;

y += dy;

}

public void draw(Graphics2D g2)

{

Rectangle2D.Double body

= new Rectangle2D.Double(x, y + width / 6,

width - 1, width / 6);

Ellipse2D.Double frontTire

= new Ellipse2D.Double(x + width / 6, y + width / 3,

width / 6, width / 6);

Ellipse2D.Double rearTire

= new Ellipse2D.Double(x + width * 2 / 3, y + width / 3,

width / 6, width / 6);

// The bottom of the front windshield

Point2D.Double r1

= new Point2D.Double(x + width / 6, y + width / 6);

// The front of the roof

Point2D.Double r2

= new Point2D.Double(x + width / 3, y);

// The rear of the roof

Point2D.Double r3

= new Point2D.Double(x + width * 2 / 3, y);

// The bottom of the rear windshield

Point2D.Double r4

= new Point2D.Double(x + width * 5 / 6, y + width / 6);

Line2D.Double frontWindshield

= new Line2D.Double(r1, r2);

Line2D.Double roofTop

= new Line2D.Double(r2, r3);

Line2D.Double rearWindshield

= new Line2D.Double(r3, r4);

g2.draw(body);

g2.draw(frontTire);

g2.draw(rearTire);

g2.draw(frontWindshield);

g2.draw(roofTop);

g2.draw(rearWindshield);

Explanation: