content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  /*
   * GRAL: GRAphing Library for Java(R)
   *
   * (C) Copyright 2009-2013 Erich Seifert <dev[at]erichseifert.de>,
   * Michael Seifert <mseifert[at]error-reports.org>
   *
   * This file is part of GRAL.
   *
   * GRAL is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * GRAL is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with GRAL.  If not, see <http://www.gnu.org/licenses/>.
   */
  package de.erichseifert.gral.data.comparators;
  
  /**
   * Class that represents a {@code DataComparator} for comparing two arrays of
   * column values at a defined index for descending order.
   * @see de.erichseifert.gral.data.DataTable#sort(DataComparator...)
   */
  public class Descending extends DataComparator {
  	/** Version id for serialization. */
  	private static final long serialVersionUID = 6834583772451304014L;
  
  	/**
  	 * Creates a new Descending object sorting according to the specified
  	 * column.
  	 * @param col Column index to be compared
  	 */
  	public Descending(int col) {
  		super(col);
  	}
  
  	/**
  	 * <p>Compares the values of two rows at the specified column for order and
  	 * returns a corresponding integer:</p>
  	 * <ul>
  	 *   <li>a negative value means {@code row1} is larger than {@code row2}</li>
  	 *   <li>0 means {@code row1} is equal to {@code row2}</li>
  	 *   <li>a positive value means {@code row1} is smaller than {@code row2}</li>
  	 * </ul>
  	 * @param row1 First value
  	 * @param row2 Second value
  	 * @return An integer number describing the order:
  	 *         a negative value if {@code row1} is larger than {@code row2},
  	 *         0 if {@code row1} is equal to {@code row2},
  	 *         a positive value if {@code row1} is smaller than {@code row2},
  	 */
  	@SuppressWarnings("unchecked")
  	public int compare(Comparable<?>[] row1, Comparable<?>[] row2) {
  		Comparable<Object> value1 = (Comparable<Object>) row1[getColumn()];
  		Comparable<Object> value2 = (Comparable<Object>) row2[getColumn()];
  
  		// null values sort as if larger than non-null values
  		if (value1 == null && value2 == null) {
  			return 0;
  		} else if (value1 == null) {
  			return -1;
  		} else if (value2 == null) {
  			return 1;
  		}
  
  		return value2.compareTo(value1);
  	}
  }
  