Lecture Notes 07 August 2013

class Point
{
  // attributes
  private double x;
  private double y;

  //  default constructor
  public Point ()
  {
    x = 0.0;
    y = 0.0;
  }

  // non-default constructor
  public Point (double x, double y)
  {
    this.x = x;
    this.y = y;
  }

  // accessors
  public double getX ()
  {
    return this.x;
  }

  public double getY ()
  {
    return this.y;
  }
  
  // mutators
  public void setX (double x)
  {
    this.x = x;
  }

  public void setY (double y)
  {
    this.y = y;
  }

  // other methods
  // distance to another Point
  public double distance (Point p)
  {
    return Math.sqrt ((this.x - p.x) * (this.x - p.x) +
                      (this.y - p.y) * (this.y - p.y));
  }

  // string representation of a point
  public String toString ()
  {
    String s = "(" + x + ", " + y + ")";
    return s;
  }

  public boolean equals (Point p)
  {
    double delta = 1.0e-18;
    return (Math.abs(this.x - p.x) < delta) && (Math.abs(this.y - p.y) < delta);
  }
}

class Line
{
  // attributes
  private Point p1;
  private Point p2;

  // default constructor
  public Line()
  {
    p1 = new Point (0, 0);
    p2 = new Point (1, 1);
  }

  // non-default constructors
  public Line (double x1, double y1, double x2, double y2)
  {
    p1 = new Point (x1, y1);
    p2 = new Point (x2, y2);
  }

  public Line (Point p, Point q)
  {
    p1 = new Point (p.getX(), p.getY());
    p2 = new Point (q.getX(), q.getY());
  }

  public boolean isParallelY()
  {
    double delta = 1.0e-18;
    return (Math.abs(p1.getX() - p2.getX()) < delta);
  }

  public double slope ()
  {
    double inf = Double.POSITIVE_INFINITY;
    if (isParallelY())
      return inf;
    return ((p2.getY() - p1.getY()) / (p2.getX() - p1.getX()));
  }
}
public class Geometry
{
  public static void main (String[] args)
  {
    Point p = new Point ();
    Point q = new Point (3, 4);
    System.out.println (p.distance(q));
    System.out.println (q.distance(p));
    System.out.println (p);
    System.out.println (q);
    
  }
}