1 . Run and study the example so that you understand all of its code.

2. Convert the class Polygon from using an array of Point2d to using a java.util.ArrayList. Since an ArrayList will both grow and keep track of the number of the number of elements referenced (Point2d objects in this case),

(a) it is not necessary to set the size of the ArrayList in a constructor.

(b) it is not necessary to keep a counter for the number of points stored in the ArrayList (

c) it is not necessary to check to see if the ArrayList is full before adding a new point.

3. Make any changes to the demonstration code in class PA8_Polygon in order to run using the newly reworked class Polygon, but otherwise keep the purpose of the code.

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Code that is given

package pa8_polygon;

public class PA8_Polygon {

public static void main(String[] args) { Polygon p = new Polygon(5); p.addPoint(new Point2d(.1, .9)); System.out.println("p - points: " + p.getPoints() + ", max points: " + p.getMaxPoints()); p.addPoint(.3, .7); System.out.println("p - points: " + p.getPoints() + ", max points: " + p.getMaxPoints()); p.addPoint(new Point2d(.5, .5)); System.out.println("p - points: " + p.getPoints() + ", max points: " + p.getMaxPoints()); p.addPoint(.4, .8); System.out.println("p - points: " + p.getPoints() + ", max points: " + p.getMaxPoints()); p.addPoint(new Point2d(.2, .5)); System.out.println("p - points: " + p.getPoints() + ", max points: " + p.getMaxPoints()); System.out.println(" p contains:"); System.out.println(p); Polygon p2 = new Polygon(10); p2.addPoint(new Point2d(.1, .9)); p2.addPoint(.3, .7); p2.addPoint(new Point2d(.5, .5)); p2.addPoint(.4, .8); p2.addPoint(new Point2d(.2, .5)); p2.addPoint(new Point2d(.9, .1)); p2.addPoint(.7, .3); p2.addPoint(new Point2d(.4, .5)); p2.addPoint(.8, .4); p2.addPoint(new Point2d(.5, .2)); System.out.println("p2 contains:"); for (int i=0; i

}

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package pa8_polygon;

public class Polygon { private Point2d[] p = null; private int points = 0; public Polygon() { p = new Point2d[3]; } public Polygon(int numPoints) { if (numPoints > 3) p = new Point2d[numPoints]; } public int getMaxPoints() { return p.length; } public int getPoints() { return points; } public boolean addPoint(Point2d point) { if (points < p.length) { p[points] = new Point2d(point.getX(), point.getY()); points++; return true; } return false; } public boolean addPoint(double x, double y) { if (points < p.length) { p[points] = new Point2d(x, y); points++; return true; } return false; } public Point2d getPoint(int index) { if (index < 0 || index >= p.length) return null; return new Point2d(p[index]); } public String toString() { String s = ""; for (Point2d q : p) s += q.toString() + " "; return s; } }

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package pa8_polygon;

public class Point2d { private double x = 0, y = 0; public Point2d() { } public Point2d(double x, double y) { setX(x); setY(y); } public Point2d(Point2d p) { setX(p.x); setY(p.y); } public void setX(double initX) { if (initX >= 0 && initX <= 1) x = initX; } public void setY(double y) { if (y >= 0 && y <= 1) this.y = y; } public double getX() { return x; } public double getY() { return y; } public String toString() { return "(" + x + "," + y + ")"; } }