Point.java

public class Point implements Comparable<Point> {
   public Point(int x, int y)                         // constructs the point (x, y)

   public   void draw()                               // draws this point
   public   void drawTo(Point that)                   // draws the line segment from this point to that point
   public String toString()                           // string representation

   public               int compareTo(Point that)     // compare two points by y-coordinates, breaking ties by x-coordinates
   public            double slopeTo(Point that)       // the slope between this point and that point
   public Comparator<Point> slopeOrder()              // compare two points by slopes they make with this point
}