/*
 *  =======================================================================
 *  LineSegment.java: A line segment is defined by the (x,y) coordinates of
 *              its two end points. 
 * 
 *  Written By: Mark Austin                                   November 2005 
 *  =======================================================================
 */

public class LineSegment {
   protected Node n1, n2; // nodal 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 ) {
      n1 = new Node( dX1, dY1 );
      n2 = new Node( dX2, dY2 );
   }

   // Get end points 1 and 2.

   public Node getNode1() { return n1; }  
   public Node getNode2() { return n2; }

   // Print details of line segment.

   public void printSegment() {

      System.out.println("Line Segment");
      System.out.println("Node 1 : (x,y) = " + n1.toString() );
      System.out.println("Node 2 : (x,y) = " + n2.toString() );
   }

   // Compute length of line segment.

   public double segmentLength() {
      double dLength;

      dLength = (n1.getX() - n2.getX())*(n1.getX() - n2.getX()) +
                (n1.getY() - n2.getY())*(n1.getY() - n2.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 );
      s2.n1.setName( "n1" );
      s2.n2.setName( "n2" );

      // 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");
   }

}