line.java

一个简单的分布计算环境

package Geometry;

public class Line {

  // Create a line from two points
  public Line(final Point start, final Point end) {
    this.start = new Point(start);
    this.end = new Point(end);
  }

  // Create a line from two coordinate pairs
  public Line(double xStart, double yStart, double xEnd, double yEnd) {
    start = new Point(xStart, yStart);      // Create the start point
    end = new Point(xEnd, yEnd);            // Create the end point
  }

  // Calculate the length of a line
  public double length() {
    return start.distance(end);             // Use the method from the Point class
  }

  // Return a point as the intersection of two lines -- called from a Line object
  public Point intersects(final Line line1) {

    Point localPoint = new Point(0, 0);

    double num =(this.end.getY() - this.start.getY()) 
              * (this.start.getX()-line1.start.getX()) 
              - (this.end.getX() - this.start.getX())
              * (this.start.getY() - line1.start.getY());

    double denom = (this.end.getY() - this.start.getY()) 
                 * (line1.end.getX() - line1.start.getX()) 
                 - (this.end.getX() - this.start.getX())
                 * (line1.end.getY() - line1.start.getY());

    localPoint.setX(line1.start.getX() + (line1.end.getX() - 
                                          line1.start.getX())*num/denom);
    localPoint.setY(line1.start.getY() + (line1.end.getY() - 
                                          line1.start.getY())*num/denom);

    return localPoint;
  }

  // Convert a line to a string 
  public String toString() {
    return "(" + start+ "):(" + end + ")";  // As "(start):(end)"
  }                                         // that is, "(x1, y1):(x2, y2)"

  // Data members
  Point start;                              // Start point of line
  Point end;                                // End point of line
}