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com.supermap.data

Class Point2D

  • java.lang.Object
    • com.supermap.data.Point2D

  • public class Point2D
extends java.lang.Object
    The instance of the point class is the point object, which is used to represent the point with double coordinate values ranging from 5.0*1e-324 to ±1.7*1e308, with 15-16 effective digits.

    The Point2D object is a very basic object for various geometric objects, for example, a GeoLine object is formed of a bunch of Point2D objects, while a GeoRegion object is also formed of a bunch of Point2D objects, except that the start point and the endpoint is identical. So when depicting the location and shape of a geometric object, the Point2D object is very necessary.

    To construct a new Point2D object, three constructors are provided. When construct a new object with the default constructor, both the x- and y-coordinate are -1.7976931348623157e+308; you can also initialize a new Point2D instance with specified x- and y-coordinate values, or create a copy of an existing Point2D object.

    Besides the methods for getting and setting the values of coordinates of the point, this class also provides methods that used to create new point with integer x-and y-coordinates with given point, and the method to offset this point etc.

    • Constructor Summary

      Constructors 
      Constructor and Description
      Point2D()
      Constructs a new Point2D object.
      Point2D(double x, double y)
      Creates a new Point2D object according to the specified arguments.
      Point2D(Point2D pt)
      Constructs a new object identical to the given Point2D object.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method and Description
      static Point2D ceiling(Point2D pt)
      Returns a Point2D object whose X, Y coordinates are the larger than or equal to the minimum integer of the X, Y coordinates of the given point.
      Point2D clone()
      Returns a copy of the current Point2D object.
      boolean equals(java.lang.Object obj)
      Specifies whether this Point2D object contains the same coordinate with the given System.Object.
      boolean equals(Point2D pt)
      Determines whether this Point2D object equals to the given Point2D object, that is whether they have the same coordinate.
      static Point2D floor(Point2D pt)
      Returns a Point2D object whose X, Y coordinates are the less than or equal to the maximum integer of the X, Y coordinates of the given point.
      static Point2D getEMPTY()
      Returns an empty point object.
      double getX()
      Returns the X-coordinate of the Point2D object.
      double getY()
      Returns the Y-coordinate of the Point2D object.
      int hashCode()
      Gets the hash code of this Point2D object.
      boolean isEmpty()
      Gets a value that indicates whether both the x-coordinate and the y-coordinate of this Point2D object are -1.7976931348623157e+308.
      void offset(double dx, double dy)
      Translates this Point2D object by the specified amount.
      static Point2D round(Point2D pt)
      Returns a new Point2D object.
      void setX(double value)
      Sets the x-coordinate of this Point2D.
      void setY(double value)
      Sets the y-coordinate of this Point2D.
      java.lang.String toString()
      Creates a readable character string of this Point2D, for instance, Point2D(2,3), and the result string format is "{X=2.0,Y=3.0}".

      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait

    • Constructor Detail

      • Point2D

        public Point2D()
        Constructs a new Point2D object.

      • Point2D

        public Point2D(double x,
               double y)
        Creates a new Point2D object according to the specified arguments.
        Parameters:
        x - The X coordinate of the Point2D.
        y - The Y coordinate of the Point2D.

      • Point2D

        public Point2D(Point2D pt)
        Constructs a new object identical to the given Point2D object.
        Parameters:
        pt - The specified Point2D object.

    • Method Detail

      • getEMPTY

        public static final Point2D getEMPTY()
        Returns an empty point object.
        Returns:
        an empty point object.
        Example:
        The code below demonstrates how to create an empty Point2D object. 
         public void getEmptyTest() {
        // Construce an empty 2D point object
        Point2D point2D = Point2D.getEMPTY();
        System.out.println(point2D.isEmpty()); // true
    }

      • isEmpty

        public boolean isEmpty()
        Gets a value that indicates whether both the x-coordinate and the y-coordinate of this Point2D object are -1.7976931348623157e+308.

        The determine precision used is equal-zero precision by default. For more information about default equal-zero precision, please refer to the Environment class.

        Returns:
        returns true if the Point2D object is empty.
        Default:
        the default value is true, that is the Point2D object is null.

      • getX

        public double getX()
        Returns the X-coordinate of the Point2D object.
        Returns:
        the X-coordinate of the Point2D object.
        Default:
        The default value is -1.79769313486232E+308.

      • setX

        public void setX(double value)
        Sets the x-coordinate of this Point2D.
        Parameters:
        value - the x-coordinate of the given Point2D object.

      • getY

        public double getY()
        Returns the Y-coordinate of the Point2D object.
        Returns:
        the Y-coordinate of the Point2D object.
        Default:
        The default value is -1.79769313486232E+308.

      • setY

        public void setY(double value)
        Sets the y-coordinate of this Point2D.
        Parameters:
        value - the y-coordinate of the given Point2D object.

      • clone

        public Point2D clone()
        Returns a copy of the current Point2D object.
        Overrides:
        clone in class java.lang.Object
        Returns:
        The new Point2D object generated from the clone operation.

      • equals

        public boolean equals(Point2D pt)
        Determines whether this Point2D object equals to the given Point2D object, that is whether they have the same coordinate. Note that the comparison is performed in terms of the equal-zero precision. For more information about equal-zero precision, please refer to the Environment class.
        Parameters:
        pt - the Point2D object to compare with the given Point2D object.
        Returns:
        true if the two objects are equal, or false otherwise.

      • ceiling

        public static Point2D ceiling(Point2D pt)
        Returns a Point2D object whose X, Y coordinates are the larger than or equal to the minimum integer of the X, Y coordinates of the given point. For instance, if the given Point2D object is (32.12, 20.67), this method will return a new Point2D object with the coordinates (33,21).
        Parameters:
        pt - the Point2D object to convert.
        Returns:
        The converted Point2D object.
        Example:
        The following example demonstrates the ceiling operation on a Point2D object. 
         public void ceilingTest() {
        // Constructs a 2D point object
        Point2D point2D = new Point2D(100.5, 100.4);
        System.out.println(point2D); // {X=100.5,Y=100.4}

        // ceiling operation
        Point2D point2D_c = Point2D.ceiling(point2D);
        System.out.println(point2D_c); // {X=101.0,Y=101.0}
    }

      • round

        public static Point2D round(Point2D pt)
        Returns a new Point2D object. If the X, Y, and Z coordinates of the given object are all integers, the new object will be equal to the given object. If the X, Y, and Z coordinates of the given object are decimal numbers, the coordinates of the new object will be integer values nearest to coordinates of the given object. If the coordinate is in the middle of two integers, the even integer will be returned.

        e.g.:

        • If the given object is (32.12, 26.67), the new object would be (32, 27, 10).
        • If the given object is (32, 26.67), the new object would be (32, 27, 10).
        • If the given object is (32.5, 25.5), the new object would be (32, 26, 10).
        Parameters:
        pt - the Point2D object to convert.
        Returns:
        The converted Point2D object.

      • floor

        public static Point2D floor(Point2D pt)
        Returns a Point2D object whose X, Y coordinates are the less than or equal to the maximum integer of the X, Y coordinates of the given point. For instance, if the given Point2D object is (32.12, 20.67), this method will return a new Point2D object with the coordinates (32,20). If the X or Y coordinate of the given Point2D object is integral value, the X or Y coordinate of the new Point2D object is the same integral value, for example: if the coordinate of the given point object is (10, 20), the coordinate of the new point object is (10, 20); if the coordinate of the given point object is (32.12, 15), the coordinate of the new point object is (32, 15);
        Parameters:
        pt - the Point2D object to convert.
        Returns:
        The converted Point2D object.
        Example:
        The following example demonstrates the floor operation on a Point2D object. 
         public void floorTest() {
        // Constructs a 2D point object
        Point2D point2D = new Point2D(100.5, 100.6);
        System.out.println(point2D); // {X=100.5,Y=100.6}

        // floor operation
        Point2D point2D_f = Point2D.floor(point2D);
        System.out.println(point2D_f); // {X=100.0,Y=100.0}
    }

      • offset

        public void offset(double dx,
                   double dy)
        Translates this Point2D object by the specified amount.
        Parameters:
        dx - the offset of the X coordinate.
        dy - the offset of the X coordinate.
        Example:
        The following example demonstrates the offset operation on a Point2D object. 
         public void offsetTest() {
        // Constructs a 2D point object
        Point2D point2D = new Point2D(100, 100);
        System.out.println(point2D); // {X=100.0,Y=100.0}

        // offset operation
        point2D.offset(20.5, -51.6);
        System.out.println(point2D); // {X=120.5,Y=48.4}
    }

      • toString

        public java.lang.String toString()
        Creates a readable character string of this Point2D, for instance, Point2D(2,3), and the result string format is "{X=2.0,Y=3.0}".
        Overrides:
        toString in class java.lang.Object
        Returns:
        A string that represents this Point2D.

      • equals

        public boolean equals(java.lang.Object obj)
        Specifies whether this Point2D object contains the same coordinate with the given System.Object.
        Overrides:
        equals in class java.lang.Object
        Parameters:
        obj - The object to be tested.
        Returns:
        a boolean, if obj is Point2D and has the same coordinates with this Point2D object, return true.

      • hashCode

        public int hashCode()
        Gets the hash code of this Point2D object.
        Overrides:
        hashCode in class java.lang.Object
        Returns:
        the hash code of this Point2D object.
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