source: josm/trunk/src/org/openstreetmap/josm/data/coor/Coordinate.java@ 627

// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.data.coor;

import java.io.Serializable;

/**
 * Base class of points of both coordinate system.
 * 
 * The variables are default package protected to allow routines in the data package
 * to access them directly.
 * 
 * As the class itself is package protected too, it is not visible outside of the data
 * package. Routines there should only use LatLon or EastNorth
 *
 * @author imi
 */ 
abstract class Coordinate implements Serializable {

        /**
         * Either easting or latitude
         */
        final double x;
        /**
         * Either northing or longitude
         */
        final double y;

        /**
         * Construct the point with latitude / longitude values.
         * The x/y values are left uninitialized.
         * 
         * @param lat Latitude of the point.
         * @param lon Longitude of the point.
         */
        Coordinate(double x, double y) {
                this.x = x;
                this.y = y;
        }

        /**
         * Return the squared distance of the northing/easting values between 
         * this and the argument.
         * 
         * This method does NOT compute a great circle distance between two 
         * locations!
         *
         * @param other The other point to calculate the distance to.
         * @return The square of the distance between this and the other point,
         *              regarding to the x/y values.
         */
        public double distanceSq(Coordinate other) {
                return (x-other.x)*(x-other.x)+(y-other.y)*(y-other.y);
        }
        
        /** 
         * Return the distance of the northing/easting values between this and
         * the argument.
         * 
         * This method does NOT compute a great circle distance between two 
         * locations!
         * 
         * @param other The other point to calculate the distance to.
         * @return The square of the distance between this and the other point,
         *              regarding to the x/y values.
         */
        public double distance(Coordinate other) {
                return Math.sqrt(distanceSq(other));
        }

        @Override public boolean equals(Object obj) {
                return obj instanceof Coordinate ? x == ((Coordinate)obj).x && ((Coordinate)obj).y == y : false;
        }

        @Override public int hashCode() {
                return (int)(x*65536+y*4096);
        }
}