public class Polygon extends Object implements Shape, Serializable
Polygon
class encapsulates a description of a
closed, twodimensional region within a coordinate space. This
region is bounded by an arbitrary number of line segments, each of
which is one side of the polygon. Internally, a polygon
comprises of a list of (x,y)
coordinate pairs, where each pair defines a vertex of the
polygon, and two successive pairs are the endpoints of a
line that is a side of the polygon. The first and final
pairs of (x,y)
points are joined by a line segment
that closes the polygon. This Polygon
is defined with
an evenodd winding rule. See
WIND_EVEN_ODD
for a definition of the evenodd winding rule.
This class's hittesting methods, which include the
contains
, intersects
and inside
methods, use the insideness definition described in the
Shape
class comments.Shape
,
Serialized FormModifier and Type  Field and Description 

protected Rectangle 
bounds
The bounds of this
Polygon . 
int 
npoints
The total number of points.

int[] 
xpoints
The array of X coordinates.

int[] 
ypoints
The array of Y coordinates.

Constructor and Description 

Polygon()
Creates an empty polygon.

Polygon(int[] xpoints,
int[] ypoints,
int npoints)
Constructs and initializes a
Polygon from the specified
parameters. 
Modifier and Type  Method and Description 

void 
addPoint(int x,
int y)
Appends the specified coordinates to this
Polygon . 
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. 
boolean 
contains(int x,
int y)
Determines whether the specified coordinates are inside this
Polygon . 
boolean 
contains(Point p)
Determines whether the specified
Point is inside this
Polygon . 
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 . 
Rectangle 
getBoundingBox()
Deprecated.
As of JDK version 1.1,
replaced by
getBounds() . 
Rectangle 
getBounds()
Gets the bounding box of this
Polygon . 
Rectangle2D 
getBounds2D()
Returns a high precision and more accurate bounding box of
the
Shape than the getBounds method. 
PathIterator 
getPathIterator(AffineTransform at)
Returns an iterator object that iterates along the boundary of this
Polygon and provides access to the geometry
of the outline of this Polygon . 
PathIterator 
getPathIterator(AffineTransform at,
double flatness)
Returns an iterator object that iterates along the boundary of
the
Shape and provides access to the geometry of the
outline of the Shape . 
boolean 
inside(int x,
int y)
Deprecated.
As of JDK version 1.1,
replaced by
contains(int, int) . 
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 . 
void 
invalidate()
Invalidates or flushes any internallycached data that depends
on the vertex coordinates of this
Polygon . 
void 
reset()
Resets this
Polygon object to an empty polygon. 
void 
translate(int deltaX,
int deltaY)
Translates the vertices of the
Polygon by
deltaX along the x axis and by
deltaY along the y axis. 
public int npoints
npoints
represents the number of valid points in this Polygon
and might be less than the number of elements in
xpoints
or ypoints
.
This value can be NULL.addPoint(int, int)
public int[] xpoints
Polygon
. The extra elements allow new points
to be added to this Polygon
without recreating this
array. The value of npoints
is equal to the
number of valid points in this Polygon
.addPoint(int, int)
public int[] ypoints
Polygon
. The extra elements allow new points
to be added to this Polygon
without recreating this
array. The value of npoints
is equal to the
number of valid points in this Polygon
.addPoint(int, int)
protected Rectangle bounds
Polygon
.
This value can be null.getBoundingBox()
,
getBounds()
public Polygon()
public Polygon(int[] xpoints, int[] ypoints, int npoints)
Polygon
from the specified
parameters.xpoints
 an array of X coordinatesypoints
 an array of Y coordinatesnpoints
 the total number of points in the
Polygon
NegativeArraySizeException
 if the value of
npoints
is negative.IndexOutOfBoundsException
 if npoints
is
greater than the length of xpoints
or the length of ypoints
.NullPointerException
 if xpoints
or
ypoints
is null
.public void reset()
Polygon
object to an empty polygon.
The coordinate arrays and the data in them are left untouched
but the number of points is reset to zero to mark the old
vertex data as invalid and to start accumulating new vertex
data at the beginning.
All internallycached data relating to the old vertices
are discarded.
Note that since the coordinate arrays from before the reset
are reused, creating a new empty Polygon
might
be more memory efficient than resetting the current one if
the number of vertices in the new polygon data is significantly
smaller than the number of vertices in the data from before the
reset.invalidate()
public void invalidate()
Polygon
.
This method should be called after any direct manipulation
of the coordinates in the xpoints
or
ypoints
arrays to avoid inconsistent results
from methods such as getBounds
or contains
that might cache data from earlier computations relating to
the vertex coordinates.getBounds()
public void translate(int deltaX, int deltaY)
Polygon
by
deltaX
along the x axis and by
deltaY
along the y axis.deltaX
 the amount to translate along the X axisdeltaY
 the amount to translate along the Y axispublic void addPoint(int x, int y)
Polygon
.
If an operation that calculates the bounding box of this
Polygon
has already been performed, such as
getBounds
or contains
, then this
method updates the bounding box.
x
 the specified X coordinatey
 the specified Y coordinategetBounds()
,
contains(java.awt.Point)
public Rectangle getBounds()
Polygon
.
The bounding box is the smallest Rectangle
whose
sides are parallel to the x and y axes of the
coordinate space, and can completely contain the Polygon
.getBounds
in interface Shape
Rectangle
that defines the bounds of this
Polygon
.Shape.getBounds2D()
@Deprecated public Rectangle getBoundingBox()
getBounds()
.Polygon
.Polygon
.public boolean contains(Point p)
Point
is inside this
Polygon
.p
 the specified Point
to be testedtrue
if the Polygon
contains the
Point
; false
otherwise.contains(double, double)
public boolean contains(int x, int y)
Polygon
.
x
 the specified X coordinate to be testedy
 the specified Y coordinate to be testedtrue
if this Polygon
contains
the specified coordinates (x,y)
;
false
otherwise.contains(double, double)
@Deprecated public boolean inside(int x, int y)
contains(int, int)
.Polygon
.x
 the specified X coordinate to be testedy
 the specified Y coordinate to be testedtrue
if this Polygon
contains
the specified coordinates (x,y)
;
false
otherwise.contains(double, double)
public Rectangle2D getBounds2D()
Shape
than the getBounds
method.
Note that there is no guarantee that the returned
Rectangle2D
is the smallest bounding box that encloses
the Shape
, only that the Shape
lies
entirely within the indicated Rectangle2D
. The
bounding box returned by this method is usually tighter than that
returned by the getBounds
method and never fails due
to overflow problems since the return value can be an instance of
the Rectangle2D
that uses double precision values to
store the dimensions.
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 Rectangle2D
bounds object according
to the contains(point)
method of the
bounds
. Specifically:
shape.contains(p)
requires bounds.contains(p)
If a point
is not inside the shape
, then it might
still be contained in the bounds
object:
bounds.contains(p)
does not imply shape.contains(p)
getBounds2D
in interface Shape
Rectangle2D
that is a
highprecision bounding box of the Shape
.Shape.getBounds()
public boolean contains(double x, double y)
Shape
, as described by the
definition of insideness.public boolean contains(Point2D p)
Point2D
is inside the boundary
of the Shape
, as described by the
definition of insideness.public boolean intersects(double x, double y, double w, double h)
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:
Shape
intersect, but
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.intersects
in interface Shape
x
 the X coordinate of the upperleft corner
of the specified rectangular areay
 the Y coordinate of the upperleft corner
of the specified rectangular areaw
 the width of the specified rectangular areah
 the height of the specified rectangular areatrue
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.Area
public boolean intersects(Rectangle2D r)
Shape
intersects the
interior of a specified Rectangle2D
.
The Shape.intersects()
method allows a Shape
implementation to conservatively return true
when:
Rectangle2D
and the
Shape
intersect, but
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.intersects
in interface Shape
r
 the specified Rectangle2D
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.Shape.intersects(double, double, double, double)
public boolean contains(double x, double y, double w, double h)
Shape
entirely contains
the specified rectangular area. All coordinates that lie inside
the rectangular area must lie within the Shape
for the
entire rectanglar area to be considered contained within the
Shape
.
The Shape.contains()
method allows a Shape
implementation to conservatively return false
when:
intersect
method returns true
and
Shape
entirely contains the rectangular area are
prohibitively expensive.
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.contains
in interface Shape
x
 the X coordinate of the upperleft corner
of the specified rectangular areay
 the Y coordinate of the upperleft corner
of the specified rectangular areaw
 the width of the specified rectangular areah
 the height of the specified rectangular areatrue
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.Area
,
Shape.intersects(double, double, double, double)
public boolean contains(Rectangle2D r)
Shape
entirely contains the
specified Rectangle2D
.
The Shape.contains()
method allows a Shape
implementation to conservatively return false
when:
intersect
method returns true
and
Shape
entirely contains the Rectangle2D
are prohibitively expensive.
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.contains
in interface Shape
r
 The specified Rectangle2D
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.Shape.contains(double, double, double, double)
public PathIterator getPathIterator(AffineTransform at)
Polygon
and provides access to the geometry
of the outline of this Polygon
. An optional
AffineTransform
can be specified so that the coordinates
returned in the iteration are transformed accordingly.getPathIterator
in interface Shape
at
 an optional AffineTransform
to be applied to the
coordinates as they are returned in the iteration, or
null
if untransformed coordinates are desiredPathIterator
object that provides access to the
geometry of this Polygon
.public PathIterator getPathIterator(AffineTransform at, double flatness)
Shape
and provides access to the geometry of the
outline of the Shape
. Only SEG_MOVETO, SEG_LINETO, and
SEG_CLOSE point types are returned by the iterator.
Since polygons are already flat, the flatness
parameter
is ignored. An optional AffineTransform
can be specified
in which case the coordinates returned in the iteration are transformed
accordingly.getPathIterator
in interface Shape
at
 an optional AffineTransform
to be applied to the
coordinates as they are returned in the iteration, or
null
if untransformed coordinates are desiredflatness
 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
endpoints. Since polygons are already flat the
flatness
parameter is ignored.PathIterator
object that provides access to the
Shape
object's geometry. Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developertargeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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