Geocoord.java

/*
 Copyright 2009-2013 The MITRE Corporation.
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
       http://www.apache.org/licenses/LICENSE-2.0
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 * **************************************************************************
 *                          NOTICE
 * This software was produced for the U. S. Government under Contract No.
 * W15P7T-12-C-F600, and is subject to the Rights in Noncommercial Computer
 * Software and Noncommercial Computer Software Documentation Clause
 * 252.227-7014 (JUN 1995)
 *
 * (c) 2012 The MITRE Corporation. All Rights Reserved.
 * **************************************************************************
 **/
package org.opensextant.placedata;

/**
 * A Geocoord represents spatial coordinates on the globe.
 */
public class Geocoord implements java.io.Serializable {
	private static final long serialVersionUID = -3313528469542406371L;
	/** Canonical form is decimal degree. */
	Double latitude;
	Double longitude;
	/** The phrase as found in the document. */
	String expression = "";
	/**
	 * Set to false if expression cannot be interpreted as meaningful lat/lon.
	 */
	private boolean isValid;

	/** Radius of the earth in kilometers, used for distance calc. */
	public static final double R = 6372.8;

	/** Empty public constructor so this class be used like a Bean. */
	public Geocoord() {
		isValid = true;
	}

	public Geocoord(double lat, double lon) {
		isValid = true;
		setLatitude(lat);
		setLongitude(lon);
	}

	/**
	 * This returns distance in kilometers.
	 * 
	 * @return distance from the given Geocoord, in kilometers.
	 */
	public Double distance(Geocoord another) {

		double lat = getLatitude();
		double lon = getLongitude();
		double lat2 = another.getLatitude();
		double lon2 = another.getLongitude();

		return distance(lat, lon, lat2, lon2);
	}

	/**
	 * This returns distance in kilometers.
	 * 
	 * @return distance from the given Geocoord, in kilometers.
	 */
	public Double distance(double lat, double lon) {

		double lat2 = getLatitude();
		double lon2 = getLongitude();

		return distance(lat, lon, lat2, lon2);

	}

	/**
	 * This returns distance in kilometers.
	 * 
	 * @return distance from the given Geocoord, in kilometers.
	 */
	public static double distance(double lat1, double lon1, double lat2, double lon2) {
		double dLat = Math.toRadians(lat2 - lat1);
		double dLon = Math.toRadians(lon2 - lon1);
		double lat1Rads = Math.toRadians(lat1);
		double lat2Rads = Math.toRadians(lat2);

		double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
				+ Math.sin(dLon / 2) * Math.sin(dLon / 2) * Math.cos(lat1Rads) * Math.cos(lat2Rads);
		double c = 2 * Math.asin(Math.sqrt(a));
		return R * c;
	}

	public Double getLatitude() {
		return latitude;
	}

	public void setLatitude(Double latitude) {
		this.latitude = latitude;
	}

	public Double getLongitude() {
		return longitude;
	}

	public void setLongitude(Double longitude) {
		this.longitude = longitude;
	}

	@Override
	public String toString() {
		if (isValid) {
			return "(" + this.latitude + "," + this.longitude + ")";
		}
		return "(NULL)";
	}
}