Module java.desktop
Package java.awt.geom

Class Path2D

  • All Implemented Interfaces:
    Shape, Cloneable
    Direct Known Subclasses:
    Path2D.Double, Path2D.Float


    public abstract class Path2D
    extends Object
    implements Shape, Cloneable
    The Path2D class provides a simple, yet flexible shape which represents an arbitrary geometric path. It can fully represent any path which can be iterated by the PathIterator interface including all of its segment types and winding rules and it implements all of the basic hit testing methods of the Shape interface.

    Use Path2D.Float when dealing with data that can be represented and used with floating point precision. Use Path2D.Double for data that requires the accuracy or range of double precision.

    Path2D provides exactly those facilities required for basic construction and management of a geometric path and implementation of the above interfaces with little added interpretation. If it is useful to manipulate the interiors of closed geometric shapes beyond simple hit testing then the Area class provides additional capabilities specifically targeted at closed figures. While both classes nominally implement the Shape interface, they differ in purpose and together they provide two useful views of a geometric shape where Path2D deals primarily with a trajectory formed by path segments and Area deals more with interpretation and manipulation of enclosed regions of 2D geometric space.

    The PathIterator interface has more detailed descriptions of the types of segments that make up a path and the winding rules that control how to determine which regions are inside or outside the path.

    Since:
    1.6
    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  Path2D.Double
      The Double class defines a geometric path with coordinates stored in double precision floating point.
      static class  Path2D.Float
      The Float class defines a geometric path with coordinates stored in single precision floating point.
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int WIND_EVEN_ODD
      An even-odd winding rule for determining the interior of a path.
      static int WIND_NON_ZERO
      A non-zero winding rule for determining the interior of a path.
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      abstract void append​(PathIterator pi, boolean connect)
      Appends the geometry of the specified PathIterator object to the path, possibly connecting the new geometry to the existing path segments with a line segment.
      void append​(Shape s, boolean connect)
      Appends the geometry of the specified Shape object to the path, possibly connecting the new geometry to the existing path segments with a line segment.
      abstract Object clone​()
      Creates a new object of the same class as this object.
      void closePath​()
      Closes the current subpath by drawing a straight line back to the coordinates of the last moveTo.
      boolean contains​(double x, double y)
      Tests if the specified coordinates are inside the boundary of the Shape, as described by the definition of insideness.
      boolean contains​(double x, double y, double w, double h)
      Tests if the interior of the Shape entirely contains the specified rectangular area.
      static boolean contains​(PathIterator pi, double x, double y)
      Tests if the specified coordinates are inside the closed boundary of the specified PathIterator.
      static boolean contains​(PathIterator pi, double x, double y, double w, double h)
      Tests if the specified rectangular area is entirely inside the closed boundary of the specified PathIterator.
      static boolean contains​(PathIterator pi, Point2D p)
      Tests if the specified Point2D is inside the closed boundary of the specified PathIterator.
      static boolean contains​(PathIterator pi, Rectangle2D r)
      Tests if the specified Rectangle2D is entirely inside the closed boundary of the specified PathIterator.
      boolean contains​(Point2D p)
      Tests if a specified Point2D is inside the boundary of the Shape, as described by the definition of insideness.
      boolean contains​(Rectangle2D r)
      Tests if the interior of the Shape entirely contains the specified Rectangle2D.
      Shape createTransformedShape​(AffineTransform at)
      Returns a new Shape representing a transformed version of this Path2D.
      abstract void curveTo​(double x1, double y1, double x2, double y2, double x3, double y3)
      Adds a curved segment, defined by three new points, to the path by drawing a Bézier curve that intersects both the current coordinates and the specified coordinates (x3,y3), using the specified points (x1,y1) and (x2,y2) as Bézier control points.
      Rectangle getBounds​()
      Returns an integer Rectangle that completely encloses the Shape.
      Point2D getCurrentPoint​()
      Returns the coordinates most recently added to the end of the path as a Point2D object.
      PathIterator getPathIterator​(AffineTransform at, double flatness)
      Returns an iterator object that iterates along the Shape boundary and provides access to a flattened view of the Shape outline geometry.
      int getWindingRule​()
      Returns the fill style winding rule.
      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.
      static boolean intersects​(PathIterator pi, double x, double y, double w, double h)
      Tests if the interior of the specified PathIterator intersects the interior of a specified set of rectangular coordinates.
      static boolean intersects​(PathIterator pi, Rectangle2D r)
      Tests if the interior of the specified PathIterator intersects the interior of a specified Rectangle2D.
      boolean intersects​(Rectangle2D r)
      Tests if the interior of the Shape intersects the interior of a specified Rectangle2D.
      abstract void lineTo​(double x, double y)
      Adds a point to the path by drawing a straight line from the current coordinates to the new specified coordinates specified in double precision.
      abstract void moveTo​(double x, double y)
      Adds a point to the path by moving to the specified coordinates specified in double precision.
      abstract void quadTo​(double x1, double y1, double x2, double y2)
      Adds a curved segment, defined by two new points, to the path by drawing a Quadratic curve that intersects both the current coordinates and the specified coordinates (x2,y2), using the specified point (x1,y1) as a quadratic parametric control point.
      void reset​()
      Resets the path to empty.
      void setWindingRule​(int rule)
      Sets the winding rule for this path to the specified value.
      abstract void transform​(AffineTransform at)
      Transforms the geometry of this path using the specified AffineTransform.
    • Method Detail

      • moveTo

        public abstract void moveTo​(double x,
                                    double y)
        Adds a point to the path by moving to the specified coordinates specified in double precision.
        Parameters:
        x - the specified X coordinate
        y - the specified Y coordinate
        Since:
        1.6
      • lineTo

        public abstract void lineTo​(double x,
                                    double y)
        Adds a point to the path by drawing a straight line from the current coordinates to the new specified coordinates specified in double precision.
        Parameters:
        x - the specified X coordinate
        y - the specified Y coordinate
        Since:
        1.6
      • quadTo

        public abstract void quadTo​(double x1,
                                    double y1,
                                    double x2,
                                    double y2)
        Adds a curved segment, defined by two new points, to the path by drawing a Quadratic curve that intersects both the current coordinates and the specified coordinates (x2,y2), using the specified point (x1,y1) as a quadratic parametric control point. All coordinates are specified in double precision.
        Parameters:
        x1 - the X coordinate of the quadratic control point
        y1 - the Y coordinate of the quadratic control point
        x2 - the X coordinate of the final end point
        y2 - the Y coordinate of the final end point
        Since:
        1.6
      • curveTo

        public abstract void curveTo​(double x1,
                                     double y1,
                                     double x2,
                                     double y2,
                                     double x3,
                                     double y3)
        Adds a curved segment, defined by three new points, to the path by drawing a Bézier curve that intersects both the current coordinates and the specified coordinates (x3,y3), using the specified points (x1,y1) and (x2,y2) as Bézier control points. All coordinates are specified in double precision.
        Parameters:
        x1 - the X coordinate of the first Bézier control point
        y1 - the Y coordinate of the first Bézier control point
        x2 - the X coordinate of the second Bézier control point
        y2 - the Y coordinate of the second Bézier control point
        x3 - the X coordinate of the final end point
        y3 - the Y coordinate of the final end point
        Since:
        1.6
      • closePath

        public final void closePath​()
        Closes the current subpath by drawing a straight line back to the coordinates of the last moveTo. If the path is already closed then this method has no effect.
        Since:
        1.6
      • append

        public final void append​(Shape s,
                                 boolean connect)
        Appends the geometry of the specified Shape object to the path, possibly connecting the new geometry to the existing path segments with a line segment. If the connect parameter is true and the path is not empty then any initial moveTo in the geometry of the appended Shape is turned into a lineTo segment. If the destination coordinates of such a connecting lineTo segment match the ending coordinates of a currently open subpath then the segment is omitted as superfluous. The winding rule of the specified Shape is ignored and the appended geometry is governed by the winding rule specified for this path.
        Parameters:
        s - the Shape whose geometry is appended to this path
        connect - a boolean to control whether or not to turn an initial moveTo segment into a lineTo segment to connect the new geometry to the existing path
        Since:
        1.6
      • append

        public abstract void append​(PathIterator pi,
                                    boolean connect)
        Appends the geometry of the specified PathIterator object to the path, possibly connecting the new geometry to the existing path segments with a line segment. If the connect parameter is true and the path is not empty then any initial moveTo in the geometry of the appended Shape is turned into a lineTo segment. If the destination coordinates of such a connecting lineTo segment match the ending coordinates of a currently open subpath then the segment is omitted as superfluous. The winding rule of the specified Shape is ignored and the appended geometry is governed by the winding rule specified for this path.
        Parameters:
        pi - the PathIterator whose geometry is appended to this path
        connect - a boolean to control whether or not to turn an initial moveTo segment into a lineTo segment to connect the new geometry to the existing path
        Since:
        1.6
      • getCurrentPoint

        public final Point2D getCurrentPoint​()
        Returns the coordinates most recently added to the end of the path as a Point2D object.
        Returns:
        a Point2D object containing the ending coordinates of the path or null if there are no points in the path.
        Since:
        1.6
      • reset

        public final void reset​()
        Resets the path to empty. The append position is set back to the beginning of the path and all coordinates and point types are forgotten.
        Since:
        1.6
      • transform

        public abstract void transform​(AffineTransform at)
        Transforms the geometry of this path using the specified AffineTransform. The geometry is transformed in place, which permanently changes the boundary defined by this object.
        Parameters:
        at - the AffineTransform used to transform the area
        Since:
        1.6
      • createTransformedShape

        public final Shape createTransformedShape​(AffineTransform at)
        Returns a new Shape representing a transformed version of this Path2D. Note that the exact type and coordinate precision of the return value is not specified for this method. The method will return a Shape that contains no less precision for the transformed geometry than this Path2D currently maintains, but it may contain no more precision either. If the tradeoff of precision vs. storage size in the result is important then the convenience constructors in the Path2D.Float and Path2D.Double subclasses should be used to make the choice explicit.
        Parameters:
        at - the AffineTransform used to transform a new Shape.
        Returns:
        a new Shape, transformed with the specified AffineTransform.
        Since:
        1.6
      • getBounds

        public final 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:
        1.6
        See Also:
        Shape.getBounds2D()
      • contains

        public static boolean contains​(PathIterator pi,
                                       double x,
                                       double y)
        Tests if the specified coordinates are inside the closed boundary of the specified PathIterator.

        This method provides a basic facility for implementors of the Shape interface to implement support for the Shape.contains(double, double) method.

        Parameters:
        pi - the specified PathIterator
        x - the specified X coordinate
        y - the specified Y coordinate
        Returns:
        true if the specified coordinates are inside the specified PathIterator; false otherwise
        Since:
        1.6
      • contains

        public static boolean contains​(PathIterator pi,
                                       Point2D p)
        Tests if the specified Point2D is inside the closed boundary of the specified PathIterator.

        This method provides a basic facility for implementors of the Shape interface to implement support for the Shape.contains(Point2D) method.

        Parameters:
        pi - the specified PathIterator
        p - the specified Point2D
        Returns:
        true if the specified coordinates are inside the specified PathIterator; false otherwise
        Since:
        1.6
      • contains

        public final boolean contains​(double x,
                                      double y)
        Tests if the specified coordinates are inside the boundary of the Shape, as described by the definition of insideness.
        Specified by:
        contains in interface Shape
        Parameters:
        x - the specified X coordinate to be tested
        y - the specified Y coordinate to be tested
        Returns:
        true if the specified coordinates are inside the Shape boundary; false otherwise.
        Since:
        1.6
      • contains

        public final boolean contains​(Point2D p)
        Tests if a specified Point2D is inside the boundary of the Shape, as described by the definition of insideness.
        Specified by:
        contains in interface Shape
        Parameters:
        p - the specified Point2D to be tested
        Returns:
        true if the specified Point2D is inside the boundary of the Shape; false otherwise.
        Since:
        1.6
      • contains

        public static boolean contains​(PathIterator pi,
                                       double x,
                                       double y,
                                       double w,
                                       double h)
        Tests if the specified rectangular area is entirely inside the closed boundary of the specified PathIterator.

        This method provides a basic facility for implementors of the Shape interface to implement support for the Shape.contains(double, double, double, double) method.

        This method object may conservatively return false in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such segments could lie entirely within the interior of the path if they are part of a path with a WIND_NON_ZERO winding rule or if the segments are retraced in the reverse direction such that the two sets of segments cancel each other out without any exterior area falling between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        Parameters:
        pi - the specified PathIterator
        x - the specified X coordinate
        y - the specified Y coordinate
        w - the width of the specified rectangular area
        h - the height of the specified rectangular area
        Returns:
        true if the specified PathIterator contains the specified rectangular area; false otherwise.
        Since:
        1.6
      • contains

        public static boolean contains​(PathIterator pi,
                                       Rectangle2D r)
        Tests if the specified Rectangle2D is entirely inside the closed boundary of the specified PathIterator.

        This method provides a basic facility for implementors of the Shape interface to implement support for the Shape.contains(Rectangle2D) method.

        This method object may conservatively return false in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such segments could lie entirely within the interior of the path if they are part of a path with a WIND_NON_ZERO winding rule or if the segments are retraced in the reverse direction such that the two sets of segments cancel each other out without any exterior area falling between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        Parameters:
        pi - the specified PathIterator
        r - a specified Rectangle2D
        Returns:
        true if the specified PathIterator contains the specified Rectangle2D; false otherwise.
        Since:
        1.6
      • contains

        public final boolean contains​(double x,
                                      double y,
                                      double w,
                                      double h)
        Tests if the interior of the Shape entirely contains the specified rectangular area. All coordinates that lie inside the rectangular area must lie within the Shape for the entire rectangular area to be considered contained within the Shape.

        The Shape.contains() method allows a Shape implementation to conservatively return false when:

        • the intersect method returns true and
        • the calculations to determine whether or not the Shape entirely contains the rectangular area are prohibitively expensive.
        This means that for some Shapes this method might return false even though the Shape contains the rectangular area. The Area class performs more accurate geometric computations than most Shape objects and therefore can be used if a more precise answer is required.

        This method object may conservatively return false in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such segments could lie entirely within the interior of the path if they are part of a path with a WIND_NON_ZERO winding rule or if the segments are retraced in the reverse direction such that the two sets of segments cancel each other out without any exterior area falling between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        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:
        true if the interior of the Shape entirely contains the specified rectangular area; false otherwise or, if the Shape contains the rectangular area and the intersects method returns true and the containment calculations would be too expensive to perform.
        Since:
        1.6
        See Also:
        Area, Shape.intersects(double, double, double, double)
      • contains

        public final boolean contains​(Rectangle2D r)
        Tests if the interior of the Shape entirely contains the specified Rectangle2D. The Shape.contains() method allows a Shape implementation to conservatively return false when:
        • the intersect method returns true and
        • the calculations to determine whether or not the Shape entirely contains the Rectangle2D are prohibitively expensive.
        This means that for some Shapes this method might return false even though the Shape contains the Rectangle2D. The Area class performs more accurate geometric computations than most Shape objects and therefore can be used if a more precise answer is required.

        This method object may conservatively return false in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such segments could lie entirely within the interior of the path if they are part of a path with a WIND_NON_ZERO winding rule or if the segments are retraced in the reverse direction such that the two sets of segments cancel each other out without any exterior area falling between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        Specified by:
        contains in interface Shape
        Parameters:
        r - The specified Rectangle2D
        Returns:
        true if the interior of the Shape entirely contains the Rectangle2D; false otherwise or, if the Shape contains the Rectangle2D and the intersects method returns true and the containment calculations would be too expensive to perform.
        Since:
        1.6
        See Also:
        Shape.contains(double, double, double, double)
      • intersects

        public static boolean intersects​(PathIterator pi,
                                         double x,
                                         double y,
                                         double w,
                                         double h)
        Tests if the interior of the specified PathIterator intersects the interior of a specified set of rectangular coordinates.

        This method provides a basic facility for implementors of the Shape interface to implement support for the Shape.intersects(double, double, double, double) method.

        This method object may conservatively return true in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such a case may occur if some set of segments of the path are retraced in the reverse direction such that the two sets of segments cancel each other out without any interior area between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        Parameters:
        pi - the specified PathIterator
        x - the specified X coordinate
        y - the specified Y coordinate
        w - the width of the specified rectangular coordinates
        h - the height of the specified rectangular coordinates
        Returns:
        true if the specified PathIterator and the interior of the specified set of rectangular coordinates intersect each other; false otherwise.
        Since:
        1.6
      • intersects

        public static boolean intersects​(PathIterator pi,
                                         Rectangle2D r)
        Tests if the interior of the specified PathIterator intersects the interior of a specified Rectangle2D.

        This method provides a basic facility for implementors of the Shape interface to implement support for the Shape.intersects(Rectangle2D) method.

        This method object may conservatively return true in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such a case may occur if some set of segments of the path are retraced in the reverse direction such that the two sets of segments cancel each other out without any interior area between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        Parameters:
        pi - the specified PathIterator
        r - the specified Rectangle2D
        Returns:
        true if the specified PathIterator and the interior of the specified Rectangle2D intersect each other; false otherwise.
        Since:
        1.6
      • intersects

        public final 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.

        This method object may conservatively return true in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such a case may occur if some set of segments of the path are retraced in the reverse direction such that the two sets of segments cancel each other out without any interior area between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        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:
        1.6
        See Also:
        Area
      • intersects

        public final 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.

        This method object may conservatively return true in cases where the specified rectangular area intersects a segment of the path, but that segment does not represent a boundary between the interior and exterior of the path. Such a case may occur if some set of segments of the path are retraced in the reverse direction such that the two sets of segments cancel each other out without any interior area between them. To determine whether segments represent true boundaries of the interior of the path would require extensive calculations involving all of the segments of the path and the winding rule and are thus beyond the scope of this implementation.

        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:
        1.6
        See Also:
        Shape.intersects(double, double, double, double)
      • getPathIterator

        public final PathIterator getPathIterator​(AffineTransform at,
                                                  double flatness)
        Returns an iterator object that iterates along the Shape boundary and provides access to a flattened view of the Shape outline geometry.

        Only SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types are returned by the iterator.

        If an optional AffineTransform is specified, the coordinates returned in the iteration are transformed accordingly.

        The amount of subdivision of the curved segments is controlled by the flatness parameter, which specifies the maximum distance that any point on the unflattened transformed curve can deviate from the returned flattened path segments. Note that a limit on the accuracy of the flattened path might be silently imposed, causing very small flattening parameters to be treated as larger values. This limit, if there is one, is defined by the particular implementation that is used.

        Each call to this method returns a fresh PathIterator object that traverses the Shape object geometry independently from any other PathIterator objects in use at the same time.

        It is recommended, but not guaranteed, that objects implementing the Shape interface isolate iterations that are in process from any changes that might occur to the original object's geometry during such iterations.

        The iterator for this class is not multi-threaded safe, which means that this Path2D class does not guarantee that modifications to the geometry of this Path2D object do not affect any iterations of that geometry that are already in process.

        Specified by:
        getPathIterator in interface Shape
        Parameters:
        at - an optional AffineTransform to be applied to the coordinates as they are returned in the iteration, or null if untransformed coordinates are desired
        flatness - the maximum distance that the line segments used to approximate the curved segments are allowed to deviate from any point on the original curve
        Returns:
        a new PathIterator that independently traverses a flattened view of the geometry of the Shape.
        Since:
        1.6
      • clone

        public abstract 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:
        1.6
        See Also:
        Cloneable