user/super/com/google/gwt/emul/java/util/Comparators.java

/*
 * Copyright 2007 Google Inc.
 *
 * 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 java.util;

import static javaemul.internal.InternalPreconditions.checkNotNull;

class Comparators {
  /*
   * This is a utility class that provides a default Comparator. This class
   * exists so Arrays and Collections can share the natural comparator without
   * having to know internals of each other.
   *
   * This class is package protected since it is not in the JRE.
   */

  /**
   * Compares two Objects according to their <i>natural ordering</i>.
   *
   * @see java.lang.Comparable
   */
  private static final Comparator<Object> NATURAL = new Comparator<Object>() {
    @Override
    public int compare(Object o1, Object o2) {
      checkNotNull(o1);
      checkNotNull(o2);
      return ((Comparable<Object>) o1).compareTo(o2);
    }
  };

  /**
   * Returns the natural Comparator.
   * <p>
   * Example:
   *
   * <pre>Comparator&lt;String&gt; compareString = Comparators.natural()</pre>
   *
   * @return the natural Comparator
   */
  public static <T> Comparator<T> natural() {
    return (Comparator<T>) NATURAL;
  }
}