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Point2D (Java 2 Platform SE 5.0) - JDK 5 Documentation v1.5.0, Java 2 SDK 英文文档

JavaTM 2 Platform
Standard Ed. 5.0

java.awt.geom
Class Point2D

java.lang.Object
  extended by java.awt.geom.Point2D
All Implemented Interfaces:
Cloneable
Direct Known Subclasses:
Point, Point2D.Double, Point2D.Float

public abstract class Point2D
extends Object
implements Cloneable

The Point2D class defines a point representing a location in (x, y) coordinate space.

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


Nested Class Summary
static class Point2D.Double
          The Double class defines a point specified in double precision.
static class Point2D.Float
          The Float class defines a point specified in float precision.
 
Constructor Summary
protected Point2D()
          This is an abstract class that cannot be instantiated directly.
 
Method Summary
 Object clone()
          Creates a new object of the same class and with the same contents as this object.
 double distance(double PX, double PY)
          Returns the distance from this Point2D to a specified point.
static double distance(double X1, double Y1, double X2, double Y2)
          Returns the distance between two points.
 double distance(Point2D pt)
          Returns the distance from this Point2D to a specified Point2D.
 double distanceSq(double PX, double PY)
          Returns the square of the distance from this Point2D to a specified point.
static double distanceSq(double X1, double Y1, double X2, double Y2)
          Returns the square of the distance between two points.
 double distanceSq(Point2D pt)
          Returns the square of the distance from this Point2D to a specified Point2D.
 boolean equals(Object obj)
          Determines whether or not two points are equal.
abstract  double getX()
          Returns the X coordinate of this Point2D in double precision.
abstract  double getY()
          Returns the Y coordinate of this Point2D in double precision.
 int hashCode()
          Returns the hashcode for this Point2D.
abstract  void setLocation(double x, double y)
          Sets the location of this Point2D to the specified double coordinates.
 void setLocation(Point2D p)
          Sets the location of this Point2D to the same coordinates as the specified Point2D object.
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Point2D

protected Point2D()
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 accessor methods below.

See Also:
Point2D.Float, Point2D.Double, Point
Method Detail

getX

public abstract double getX()
Returns the X coordinate of this Point2D in double precision.

Returns:
the X coordinate of this Point2D.
Since:
1.2

getY

public abstract double getY()
Returns the Y coordinate of this Point2D in double precision.

Returns:
the Y coordinate of this Point2D.
Since:
1.2

setLocation

public abstract void setLocation(double x,
                                 double y)
Sets the location of this Point2D to the specified double coordinates.

Parameters:
x, y - the coordinates of this Point2D
Since:
1.2

setLocation

public void setLocation(Point2D p)
Sets the location of this Point2D to the same coordinates as the specified Point2D object.

Parameters:
p - the specified Point2D the which to set this Point2D
Since:
1.2

distanceSq

public static double distanceSq(double X1,
                                double Y1,
                                double X2,
                                double Y2)
Returns the square of the distance between two points.

Parameters:
X1, Y1 - the coordinates of the first point
X2, Y2 - the coordinates of the second point
Returns:
the square of the distance between the two sets of specified coordinates.

distance

public static double distance(double X1,
                              double Y1,
                              double X2,
                              double Y2)
Returns the distance between two points.

Parameters:
X1, Y1 - the coordinates of the first point
X2, Y2 - the coordinates of the second point
Returns:
the distance between the two sets of specified coordinates.

distanceSq

public double distanceSq(double PX,
                         double PY)
Returns the square of the distance from this Point2D to a specified point.

Parameters:
PX, PY - the coordinates of the other point
Returns:
the square of the distance between this Point2D and the specified point.

distanceSq

public double distanceSq(Point2D pt)
Returns the square of the distance from this Point2D to a specified Point2D.

Parameters:
pt - the specified Point2D
Returns:
the square of the distance between this Point2D to a specified Point2D.

distance

public double distance(double PX,
                       double PY)
Returns the distance from this Point2D to a specified point.

Parameters:
PX, PY - the coordinates of the specified Point2D
Returns:
the distance between this Point2D and a specified point.

distance

public double distance(Point2D pt)
Returns the distance from this Point2D to a specified Point2D.

Parameters:
pt - the specified Point2D
Returns:
the distance between this Point2D and the specified Point2D.

clone

public Object clone()
Creates a new object of the same class and with the same contents 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

hashCode

public int hashCode()
Returns the hashcode for this Point2D.

Overrides:
hashCode in class Object
Returns:
a hash code for this Point2D.
See Also:
Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)
Determines whether or not two points are equal. Two instances of Point2D are equal if the values of their x and y member fields, representing their position in the coordinate space, are the same.

Overrides:
equals in class Object
Parameters:
obj - an object to be compared with this Point2D
Returns:
true if the object to be compared is an instance of Point2D and has the same values; false otherwise.
Since:
1.2
See Also:
Object.hashCode(), Hashtable

JavaTM 2 Platform
Standard Ed. 5.0

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.