Module java.desktop
Package java.awt.geom

Class Line2D

  • All Implemented Interfaces:
    Shape, Cloneable
    Direct Known Subclasses:
    Line2D.Double, Line2D.Float

    public abstract class Line2D
extends Object
implements Shape, Cloneable
    This Line2D represents a line segment in (x,y) coordinate space.

    This class is only the abstract superclass for all objects that store a 2D line segment. The actual storage representation of the coordinates is left to the subclass.

    Since:
    1.2

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  Line2D.Double
      A line segment specified with double coordinates.
      static class  Line2D.Float
      A line segment specified with float coordinates.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected Line2D​()
      This is an abstract class that cannot be instantiated directly.

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      Object clone​()
      Creates a new object of the same class as this object.
      boolean contains​(double x, double y)
      Tests if a specified coordinate is inside the boundary of this Line2D.
      boolean contains​(double x, double y, double w, double h)
      Tests if the interior of this Line2D entirely contains the specified set of rectangular coordinates.
      boolean contains​(Point2D p)
      Tests if a given Point2D is inside the boundary of this Line2D.
      boolean contains​(Rectangle2D r)
      Tests if the interior of this Line2D entirely contains the specified Rectangle2D.
      Rectangle getBounds​()
      Returns an integer Rectangle that completely encloses the Shape.
      abstract Point2D getP1​()
      Returns the start Point2D of this Line2D.
      abstract Point2D getP2​()
      Returns the end Point2D of this Line2D.
      PathIterator getPathIterator​(AffineTransform at)
      Returns an iteration object that defines the boundary of this Line2D.
      PathIterator getPathIterator​(AffineTransform at, double flatness)
      Returns an iteration object that defines the boundary of this flattened Line2D.
      abstract double getX1​()
      Returns the X coordinate of the start point in double precision.
      abstract double getX2​()
      Returns the X coordinate of the end point in double precision.
      abstract double getY1​()
      Returns the Y coordinate of the start point in double precision.
      abstract double getY2​()
      Returns the Y coordinate of the end point in double precision.
      boolean intersects​(double x, double y, double w, double h)
      Tests if the interior of the Shape intersects the interior of a specified rectangular area.
      boolean intersects​(Rectangle2D r)
      Tests if the interior of the Shape intersects the interior of a specified Rectangle2D.
      boolean intersectsLine​(double x1, double y1, double x2, double y2)
      Tests if the line segment from (x1,y1) to (x2,y2) intersects this line segment.
      boolean intersectsLine​(Line2D l)
      Tests if the specified line segment intersects this line segment.
      static boolean linesIntersect​(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4)
      Tests if the line segment from (x1,y1) to (x2,y2) intersects the line segment from (x3,y3) to (x4,y4).
      double ptLineDist​(double px, double py)
      Returns the distance from a point to this line.
      static double ptLineDist​(double x1, double y1, double x2, double y2, double px, double py)
      Returns the distance from a point to a line.
      double ptLineDist​(Point2D pt)
      Returns the distance from a Point2D to this line.
      double ptLineDistSq​(double px, double py)
      Returns the square of the distance from a point to this line.
      static double ptLineDistSq​(double x1, double y1, double x2, double y2, double px, double py)
      Returns the square of the distance from a point to a line.
      double ptLineDistSq​(Point2D pt)
      Returns the square of the distance from a specified Point2D to this line.
      double ptSegDist​(double px, double py)
      Returns the distance from a point to this line segment.
      static double ptSegDist​(double x1, double y1, double x2, double y2, double px, double py)
      Returns the distance from a point to a line segment.
      double ptSegDist​(Point2D pt)
      Returns the distance from a Point2D to this line segment.
      double ptSegDistSq​(double px, double py)
      Returns the square of the distance from a point to this line segment.
      static double ptSegDistSq​(double x1, double y1, double x2, double y2, double px, double py)
      Returns the square of the distance from a point to a line segment.
      double ptSegDistSq​(Point2D pt)
      Returns the square of the distance from a Point2D to this line segment.
      int relativeCCW​(double px, double py)
      Returns an indicator of where the specified point (px,py) lies with respect to this line segment.
      static int relativeCCW​(double x1, double y1, double x2, double y2, double px, double py)
      Returns an indicator of where the specified point (px,py) lies with respect to the line segment from (x1,y1) to (x2,y2).
      int relativeCCW​(Point2D p)
      Returns an indicator of where the specified Point2D lies with respect to this line segment.
      abstract void setLine​(double x1, double y1, double x2, double y2)
      Sets the location of the end points of this Line2D to the specified double coordinates.
      void setLine​(Line2D l)
      Sets the location of the end points of this Line2D to the same as those end points of the specified Line2D.
      void setLine​(Point2D p1, Point2D p2)
      Sets the location of the end points of this Line2D to the specified Point2D coordinates.

    • Constructor Detail

      • Line2D

        protected Line2D​()
        This is an abstract class that cannot be instantiated directly. Type-specific implementation subclasses are available for instantiation and provide a number of formats for storing the information necessary to satisfy the various accessory methods below.
        Since:
        1.2
        See Also:
        Line2D.Float, Line2D.Double

    • Method Detail

      • getX1

        public abstract double getX1​()
        Returns the X coordinate of the start point in double precision.
        Returns:
        the X coordinate of the start point of this Line2D object.
        Since:
        1.2

      • getY1

        public abstract double getY1​()
        Returns the Y coordinate of the start point in double precision.
        Returns:
        the Y coordinate of the start point of this Line2D object.
        Since:
        1.2

      • getP1

        public abstract Point2D getP1​()
        Returns the start Point2D of this Line2D.
        Returns:
        the start Point2D of this Line2D.
        Since:
        1.2

      • getX2

        public abstract double getX2​()
        Returns the X coordinate of the end point in double precision.
        Returns:
        the X coordinate of the end point of this Line2D object.
        Since:
        1.2

      • getY2

        public abstract double getY2​()
        Returns the Y coordinate of the end point in double precision.
        Returns:
        the Y coordinate of the end point of this Line2D object.
        Since:
        1.2

      • getP2

        public abstract Point2D getP2​()
        Returns the end Point2D of this Line2D.
        Returns:
        the end Point2D of this Line2D.
        Since:
        1.2

      • setLine

        public abstract void setLine​(double x1,
                             double y1,
                             double x2,
                             double y2)
        Sets the location of the end points of this Line2D to the specified double coordinates.
        Parameters:
        x1 - the X coordinate of the start point
        y1 - the Y coordinate of the start point
        x2 - the X coordinate of the end point
        y2 - the Y coordinate of the end point
        Since:
        1.2

      • setLine

        public void setLine​(Point2D p1,
                    Point2D p2)
        Sets the location of the end points of this Line2D to the specified Point2D coordinates.
        Parameters:
        p1 - the start Point2D of the line segment
        p2 - the end Point2D of the line segment
        Since:
        1.2

      • setLine

        public void setLine​(Line2D l)
        Sets the location of the end points of this Line2D to the same as those end points of the specified Line2D.
        Parameters:
        l - the specified Line2D
        Since:
        1.2

      • relativeCCW

        public static int relativeCCW​(double x1,
                              double y1,
                              double x2,
                              double y2,
                              double px,
                              double py)
        Returns an indicator of where the specified point (px,py) lies with respect to the line segment from (x1,y1) to (x2,y2). The return value can be either 1, -1, or 0 and indicates in which direction the specified line must pivot around its first end point, (x1,y1), in order to point at the specified point (px,py).

        A return value of 1 indicates that the line segment must turn in the direction that takes the positive X axis towards the negative Y axis. In the default coordinate system used by Java 2D, this direction is counterclockwise.

        A return value of -1 indicates that the line segment must turn in the direction that takes the positive X axis towards the positive Y axis. In the default coordinate system, this direction is clockwise.

        A return value of 0 indicates that the point lies exactly on the line segment. Note that an indicator value of 0 is rare and not useful for determining collinearity because of floating point rounding issues.

        If the point is colinear with the line segment, but not between the end points, then the value will be -1 if the point lies "beyond (x1,y1)" or 1 if the point lies "beyond (x2,y2)".

        Parameters:
        x1 - the X coordinate of the start point of the specified line segment
        y1 - the Y coordinate of the start point of the specified line segment
        x2 - the X coordinate of the end point of the specified line segment
        y2 - the Y coordinate of the end point of the specified line segment
        px - the X coordinate of the specified point to be compared with the specified line segment
        py - the Y coordinate of the specified point to be compared with the specified line segment
        Returns:
        an integer that indicates the position of the third specified coordinates with respect to the line segment formed by the first two specified coordinates.
        Since:
        1.2

      • relativeCCW

        public int relativeCCW​(double px,
                       double py)
        Returns an indicator of where the specified point (px,py) lies with respect to this line segment. See the method comments of relativeCCW(double, double, double, double, double, double) to interpret the return value.
        Parameters:
        px - the X coordinate of the specified point to be compared with this Line2D
        py - the Y coordinate of the specified point to be compared with this Line2D
        Returns:
        an integer that indicates the position of the specified coordinates with respect to this Line2D
        Since:
        1.2
        See Also:
        relativeCCW(double, double, double, double, double, double)

      • linesIntersect

        public static boolean linesIntersect​(double x1,
                                     double y1,
                                     double x2,
                                     double y2,
                                     double x3,
                                     double y3,
                                     double x4,
                                     double y4)
        Tests if the line segment from (x1,y1) to (x2,y2) intersects the line segment from (x3,y3) to (x4,y4).
        Parameters:
        x1 - the X coordinate of the start point of the first specified line segment
        y1 - the Y coordinate of the start point of the first specified line segment
        x2 - the X coordinate of the end point of the first specified line segment
        y2 - the Y coordinate of the end point of the first specified line segment
        x3 - the X coordinate of the start point of the second specified line segment
        y3 - the Y coordinate of the start point of the second specified line segment
        x4 - the X coordinate of the end point of the second specified line segment
        y4 - the Y coordinate of the end point of the second specified line segment
        Returns:
        true if the first specified line segment and the second specified line segment intersect each other; false otherwise.
        Since:
        1.2

      • intersectsLine

        public boolean intersectsLine​(double x1,
                              double y1,
                              double x2,
                              double y2)
        Tests if the line segment from (x1,y1) to (x2,y2) intersects this line segment.
        Parameters:
        x1 - the X coordinate of the start point of the specified line segment
        y1 - the Y coordinate of the start point of the specified line segment
        x2 - the X coordinate of the end point of the specified line segment
        y2 - the Y coordinate of the end point of the specified line segment
        Returns:
        true if this line segment and the specified line segment intersect each other; false otherwise.
        Since:
        1.2

      • intersectsLine

        public boolean intersectsLine​(Line2D l)
        Tests if the specified line segment intersects this line segment.
        Parameters:
        l - the specified Line2D
        Returns:
        true if this line segment and the specified line segment intersect each other; false otherwise.
        Since:
        1.2

      • ptSegDistSq

        public static double ptSegDistSq​(double x1,
                                 double y1,
                                 double x2,
                                 double y2,
                                 double px,
                                 double py)
        Returns the square of the distance from a point to a line segment. The distance measured is the distance between the specified point and the closest point between the specified end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.
        Parameters:
        x1 - the X coordinate of the start point of the specified line segment
        y1 - the Y coordinate of the start point of the specified line segment
        x2 - the X coordinate of the end point of the specified line segment
        y2 - the Y coordinate of the end point of the specified line segment
        px - the X coordinate of the specified point being measured against the specified line segment
        py - the Y coordinate of the specified point being measured against the specified line segment
        Returns:
        a double value that is the square of the distance from the specified point to the specified line segment.
        Since:
        1.2
        See Also:
        ptLineDistSq(double, double, double, double, double, double)

      • ptSegDist

        public static double ptSegDist​(double x1,
                               double y1,
                               double x2,
                               double y2,
                               double px,
                               double py)
        Returns the distance from a point to a line segment. The distance measured is the distance between the specified point and the closest point between the specified end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.
        Parameters:
        x1 - the X coordinate of the start point of the specified line segment
        y1 - the Y coordinate of the start point of the specified line segment
        x2 - the X coordinate of the end point of the specified line segment
        y2 - the Y coordinate of the end point of the specified line segment
        px - the X coordinate of the specified point being measured against the specified line segment
        py - the Y coordinate of the specified point being measured against the specified line segment
        Returns:
        a double value that is the distance from the specified point to the specified line segment.
        Since:
        1.2
        See Also:
        ptLineDist(double, double, double, double, double, double)

      • ptSegDistSq

        public double ptSegDistSq​(double px,
                          double py)
        Returns the square of the distance from a point to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.
        Parameters:
        px - the X coordinate of the specified point being measured against this line segment
        py - the Y coordinate of the specified point being measured against this line segment
        Returns:
        a double value that is the square of the distance from the specified point to the current line segment.
        Since:
        1.2
        See Also:
        ptLineDistSq(double, double)

      • ptSegDistSq

        public double ptSegDistSq​(Point2D pt)
        Returns the square of the distance from a Point2D to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.
        Parameters:
        pt - the specified Point2D being measured against this line segment.
        Returns:
        a double value that is the square of the distance from the specified Point2D to the current line segment.
        Since:
        1.2
        See Also:
        ptLineDistSq(Point2D)

      • ptSegDist

        public double ptSegDist​(double px,
                        double py)
        Returns the distance from a point to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.
        Parameters:
        px - the X coordinate of the specified point being measured against this line segment
        py - the Y coordinate of the specified point being measured against this line segment
        Returns:
        a double value that is the distance from the specified point to the current line segment.
        Since:
        1.2
        See Also:
        ptLineDist(double, double)

      • ptSegDist

        public double ptSegDist​(Point2D pt)
        Returns the distance from a Point2D to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.
        Parameters:
        pt - the specified Point2D being measured against this line segment
        Returns:
        a double value that is the distance from the specified Point2D to the current line segment.
        Since:
        1.2
        See Also:
        ptLineDist(Point2D)

      • ptLineDistSq

        public static double ptLineDistSq​(double x1,
                                  double y1,
                                  double x2,
                                  double y2,
                                  double px,
                                  double py)
        Returns the square of the distance from a point to a line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by the specified coordinates. If the specified point intersects the line, this method returns 0.0.
        Parameters:
        x1 - the X coordinate of the start point of the specified line
        y1 - the Y coordinate of the start point of the specified line
        x2 - the X coordinate of the end point of the specified line
        y2 - the Y coordinate of the end point of the specified line
        px - the X coordinate of the specified point being measured against the specified line
        py - the Y coordinate of the specified point being measured against the specified line
        Returns:
        a double value that is the square of the distance from the specified point to the specified line.
        Since:
        1.2
        See Also:
        ptSegDistSq(double, double, double, double, double, double)

      • ptLineDist

        public static double ptLineDist​(double x1,
                                double y1,
                                double x2,
                                double y2,
                                double px,
                                double py)
        Returns the distance from a point to a line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by the specified coordinates. If the specified point intersects the line, this method returns 0.0.
        Parameters:
        x1 - the X coordinate of the start point of the specified line
        y1 - the Y coordinate of the start point of the specified line
        x2 - the X coordinate of the end point of the specified line
        y2 - the Y coordinate of the end point of the specified line
        px - the X coordinate of the specified point being measured against the specified line
        py - the Y coordinate of the specified point being measured against the specified line
        Returns:
        a double value that is the distance from the specified point to the specified line.
        Since:
        1.2
        See Also:
        ptSegDist(double, double, double, double, double, double)

      • ptLineDistSq

        public double ptLineDistSq​(double px,
                           double py)
        Returns the square of the distance from a point to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.
        Parameters:
        px - the X coordinate of the specified point being measured against this line
        py - the Y coordinate of the specified point being measured against this line
        Returns:
        a double value that is the square of the distance from a specified point to the current line.
        Since:
        1.2
        See Also:
        ptSegDistSq(double, double)

      • ptLineDistSq

        public double ptLineDistSq​(Point2D pt)
        Returns the square of the distance from a specified Point2D to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.
        Parameters:
        pt - the specified Point2D being measured against this line
        Returns:
        a double value that is the square of the distance from a specified Point2D to the current line.
        Since:
        1.2
        See Also:
        ptSegDistSq(Point2D)

      • ptLineDist

        public double ptLineDist​(double px,
                         double py)
        Returns the distance from a point to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.
        Parameters:
        px - the X coordinate of the specified point being measured against this line
        py - the Y coordinate of the specified point being measured against this line
        Returns:
        a double value that is the distance from a specified point to the current line.
        Since:
        1.2
        See Also:
        ptSegDist(double, double)

      • ptLineDist

        public double ptLineDist​(Point2D pt)
        Returns the distance from a Point2D to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.
        Parameters:
        pt - the specified Point2D being measured
        Returns:
        a double value that is the distance from a specified Point2D to the current line.
        Since:
        1.2
        See Also:
        ptSegDist(Point2D)

      • contains

        public boolean contains​(double x,
                        double y)
        Tests if a specified coordinate is inside the boundary of this Line2D. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.
        Specified by:
        contains in interface Shape
        Parameters:
        x - the X coordinate of the specified point to be tested
        y - the Y coordinate of the specified point to be tested
        Returns:
        false because a Line2D contains no area.
        Since:
        1.2

      • contains

        public boolean contains​(Point2D p)
        Tests if a given Point2D is inside the boundary of this Line2D. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.
        Specified by:
        contains in interface Shape
        Parameters:
        p - the specified Point2D to be tested
        Returns:
        false because a Line2D contains no area.
        Since:
        1.2

      • intersects

        public boolean intersects​(double x,
                          double y,
                          double w,
                          double h)
        Tests if the interior of the Shape intersects the interior of a specified rectangular area. The rectangular area is considered to intersect the Shape if any point is contained in both the interior of the Shape and the specified rectangular area.

        The Shape.intersects() method allows a Shape implementation to conservatively return true when:

        • there is a high probability that the rectangular area and the Shape intersect, but
        • the calculations to accurately determine this intersection are prohibitively expensive.
        This means that for some Shapes this method might return true even though the rectangular area does not intersect the Shape. The Area class performs more accurate computations of geometric intersection than most Shape objects and therefore can be used if a more precise answer is required.
        Specified by:
        intersects in interface Shape
        Parameters:
        x - the X coordinate of the upper-left corner of the specified rectangular area
        y - the Y coordinate of the upper-left corner of the specified rectangular area
        w - the width of the specified rectangular area
        h - the height of the specified rectangular area
        Returns:
        true if the interior of the Shape and the interior of the rectangular area intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform; false otherwise.
        Since:
        1.2
        See Also:
        Area

      • intersects

        public boolean intersects​(Rectangle2D r)
        Tests if the interior of the Shape intersects the interior of a specified Rectangle2D. The Shape.intersects() method allows a Shape implementation to conservatively return true when:
        • there is a high probability that the Rectangle2D and the Shape intersect, but
        • the calculations to accurately determine this intersection are prohibitively expensive.
        This means that for some Shapes this method might return true even though the Rectangle2D does not intersect the Shape. The Area class performs more accurate computations of geometric intersection than most Shape objects and therefore can be used if a more precise answer is required.
        Specified by:
        intersects in interface Shape
        Parameters:
        r - the specified Rectangle2D
        Returns:
        true if the interior of the Shape and the interior of the specified Rectangle2D intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform; false otherwise.
        Since:
        1.2
        See Also:
        Shape.intersects(double, double, double, double)

      • contains

        public boolean contains​(double x,
                        double y,
                        double w,
                        double h)
        Tests if the interior of this Line2D entirely contains the specified set of rectangular coordinates. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.
        Specified by:
        contains in interface Shape
        Parameters:
        x - the X coordinate of the upper-left corner of the specified rectangular area
        y - the Y coordinate of the upper-left corner of the specified rectangular area
        w - the width of the specified rectangular area
        h - the height of the specified rectangular area
        Returns:
        false because a Line2D contains no area.
        Since:
        1.2
        See Also:
        Area, Shape.intersects(double, double, double, double)

      • contains

        public boolean contains​(Rectangle2D r)
        Tests if the interior of this Line2D entirely contains the specified Rectangle2D. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.
        Specified by:
        contains in interface Shape
        Parameters:
        r - the specified Rectangle2D to be tested
        Returns:
        false because a Line2D contains no area.
        Since:
        1.2
        See Also:
        Shape.contains(double, double, double, double)

      • getBounds

        public Rectangle getBounds​()
        Returns an integer Rectangle that completely encloses the Shape. Note that there is no guarantee that the returned Rectangle is the smallest bounding box that encloses the Shape, only that the Shape lies entirely within the indicated Rectangle. The returned Rectangle might also fail to completely enclose the Shape if the Shape overflows the limited range of the integer data type. The getBounds2D method generally returns a tighter bounding box due to its greater flexibility in representation.

        Note that the definition of insideness can lead to situations where points on the defining outline of the shape may not be considered contained in the returned bounds object, but only in cases where those points are also not considered contained in the original shape.

        If a point is inside the shape according to the contains(point) method, then it must be inside the returned Rectangle bounds object according to the contains(point) method of the bounds. Specifically:

        shape.contains(x,y) requires bounds.contains(x,y)

        If a point is not inside the shape, then it might still be contained in the bounds object:

        bounds.contains(x,y) does not imply shape.contains(x,y)

        Specified by:
        getBounds in interface Shape
        Returns:
        an integer Rectangle that completely encloses the Shape.
        Since:
        1.2
        See Also:
        Shape.getBounds2D()

      • getPathIterator

        public PathIterator getPathIterator​(AffineTransform at)
        Returns an iteration object that defines the boundary of this Line2D. The iterator for this class is not multi-threaded safe, which means that this Line2D class does not guarantee that modifications to the geometry of this Line2D object do not affect any iterations of that geometry that are already in process.
        Specified by:
        getPathIterator in interface Shape
        Parameters:
        at - the specified AffineTransform
        Returns:
        a PathIterator that defines the boundary of this Line2D.
        Since:
        1.2

      • getPathIterator

        public PathIterator getPathIterator​(AffineTransform at,
                                    double flatness)
        Returns an iteration object that defines the boundary of this flattened Line2D. The iterator for this class is not multi-threaded safe, which means that this Line2D class does not guarantee that modifications to the geometry of this Line2D object do not affect any iterations of that geometry that are already in process.
        Specified by:
        getPathIterator in interface Shape
        Parameters:
        at - the specified AffineTransform
        flatness - the maximum amount that the control points for a given curve can vary from colinear before a subdivided curve is replaced by a straight line connecting the end points. Since a Line2D object is always flat, this parameter is ignored.
        Returns:
        a PathIterator that defines the boundary of the flattened Line2D
        Since:
        1.2

      • clone

        public Object clone​()
        Creates a new object of the same class as this object.
        Overrides:
        clone in class Object
        Returns:
        a clone of this instance.
        Throws:
        OutOfMemoryError - if there is not enough memory.
        Since:
        1.2
        See Also:
        Cloneable