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.util;
  
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * Abstract class that contains utility functions for creating data structures
   * and for working with data sources and values.
   */
  public abstract class DataUtils {
  	/**
  	 * Default constructor that prevents creation of class.
  	 */
  	private DataUtils() {
  		throw new UnsupportedOperationException();
  	}
  
  	/**
  	 * Creates a mapping from two arrays, one with keys, one with values.
  	 * @param <K> Data type of the keys.
  	 * @param <V> Data type of the values.
  	 * @param keys Array containing the keys.
  	 * @param values Array containing the values.
  	 * @return Map with keys and values from the specified arrays.
  	 */
  	public static <K, V> Map<K, V> map(K[] keys, V[] values) {
  		// Check for valid parameters
  		if (keys.length != values.length) {
  			throw new IllegalArgumentException(
  				"Could not create the map because the number of keys and values differs.");
  		}
  		// Fill map with keys and values
  		Map<K, V> map = new HashMap<K, V>();
  		for (int i = 0; i < keys.length; i++) {
  			K key = keys[i];
  			V value = values[i];
  			map.put(key, value);
  		}
  		return map;
  	}
  
  	/**
  	 * Returns the double value of the {@code Number} object or the specified
  	 * default value if the object is {@code null}.
  	 * @param n Number object.
  	 * @param defaultValue Default value.
  	 * @return Double value of the {@code Number} object or the default value
  	 *         if the object is {@code null}
  	 */
  	public static double getValueOrDefault(Number n, double defaultValue) {
  		if (n == null) {
  			return defaultValue;
  		}
  		return n.doubleValue();
  	}
  }
  