public void setLengthFromTail(double length) {
public void setLengthFromTail(PathLength length) {
    public void setLengthFromTail(double length) {	int xx = x1;	int yy = y1;	x1 = x2;	y1 = y2;	x2 = xx;	y2 = yy;	setLength(length);	xx = x1;	yy = y1;	x1 = x2;	y1 = y2;	x2 = xx;	y2 = yy;    }