/*
 *  =========================================================
 *  Definition of class LineSegment:
 * 
 *  A line segment is defined by the (x,y) coordinates of
 *  its two end points. 
 * 
 *  Written By : Mark Austin                     October 1997 
 *  =========================================================
 */

public class LineSegment {
   protected Point p1, p2; // points defining the LineSegment

   // Constructor method : just create instance of class.

   public LineSegment() { }

   // Create instance of class and set (x,y) coordinates.

   public LineSegment( double dX1, double dY1,
                       double dX2, double dY2 ) {

      setLineSegment( dX1, dY1, dX2, dY2 );
   }

   // Set x and y coordinates of LineSegment.

   public void setLineSegment( double dX1, double dY1,
                               double dX2, double dY2 ) {
      p1 = new Point( dX1, dY1 );
      p2 = new Point( dX2, dY2 );
   }

   // Get end points 1 and 2.

   public Point getPoint1() { return p1; }  
   public Point getPoint2() { return p2; }

   // Print details of line segment.

   public void printSegment() {

      System.out.println("Line Segment");
      System.out.println("Point 1 : (x,y) = " + p1.toString() );
      System.out.println("Point 2 : (x,y) = " + p2.toString() );
   }

   // Compute length of line segment.

   public double segmentLength() {
      double dLength;

      dLength = (p1.getX() - p2.getX())*(p1.getX() - p2.getX()) +
                (p1.getY() - p2.getY())*(p1.getY() - p2.getY());

      return ((double) Math.sqrt(dLength));
   }

   // Exercise methods in line segment class.

   public static void main( String args[] ) {
   double dX, dY;

      System.out.println("LineSegment test program");
      System.out.println("===============================");

      // Create two new line segments.

      LineSegment s1 = new LineSegment();
      s1.setLineSegment( 1.0, 1.0, 4.0, 5.0 );
      LineSegment s2 = new LineSegment( 1.5, 1.5, 1.5, 4.5 );

      // Print details of line segments.

      s1.printSegment();
      s2.printSegment();

      // Compute length of line segments.

      System.out.println("Segment1 has length : " + s1.segmentLength());
      System.out.println("Segment2 has length : " + s2.segmentLength());

      // End of exercise.

      System.out.println("===============================");
      System.out.println("End of LineSegment test program");
   }
}