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Java Simplified. Extensions and Useful Constructs for the Java Platform. Codeprimate Elements (a.k.a. cp-elements) is a Java library and micro-framework used to simplify the development of software applications written in Java. Elements packages several APIs into one library in order to address various application concerns and aspects of software design and development collectively and conveniently. Elements is a highly simple, yet robust and proven library built on solid OO principles, software design patterns and best practices to effectively solve common and reoccurring problems in software development.

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/*
 * Copyright 2016 Author or Authors.
 *
 * 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.
 */

package org.cp.elements.util;

import java.util.Comparator;

/**
 * The ComparatorUtils class provides common functionality for ordering operations using the Comparable
 * and Comparator interfaces.
 *
 * @author John J. Blum
 * @see java.lang.Comparable
 * @see java.util.Comparator
 * @since 1.0.0
 */
@SuppressWarnings("unused")
public abstract class ComparatorUtils {

  /**
   * Compares two Comparable objects for absolute ordering, ignoring possible null values.  Null values are
   * ordered last.
   *
   * @param obj1 the Comparable object being compared with obj2.
   * @param obj2 the Comparable object being compared with obj1.
   * @param  the type of Comparable objects in the comparison.
   * @return a integer value indicating the absolute ordering of the Comparable objects as defined by
   * their natural ordering.
   * @see java.lang.Comparable
   */
  public static > int compareIgnoreNull(final T obj1, final T obj2) {
    return (obj1 == null ? 1 : (obj2 == null ? -1 : obj1.compareTo(obj2)));
  }

  /**
   * Inverts the result of the Comparator.  Used to implement a descending sort order.
   *
   * @param comparator the Comparator to invert.
   * @param  the type of Comparable objects in the comparison.
   * @return a Comparator wrapper around the specified Comparator inverting the result of the comparison.
   * @see java.util.Comparator
   */
  public static  Comparator invert(final Comparator comparator) {
    return (obj1, obj2) -> (-1 * comparator.compare(obj1, obj2));
  }

}