code: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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.apache.commons.io.comparator;
  
  import java.io.File;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  
  /**
   * Abstract file {@link Comparator} which provides sorting for file arrays and lists.
   *
   * @version $Revision: 1.1.2.1 $ $Date: 2011/01/15 20:32:25 $
   * @since Commons IO 2.0
   */
  abstract class AbstractFileComparator implements Comparator<File> {
  
      /**
       * Sort an array of files.
       * <p>
       * This method uses {@link Arrays#sort(Object[], Comparator)}
       * and returns the original array.
       *
       * @param files The files to sort, may be null
       * @return The sorted array
       * @since Commons IO 2.0
       */
      public File[] sort(File... files) {
          if (files != null) {
              Arrays.sort(files, this);
          }
          return files;
      }
  
      /**
       * Sort a List of files.
       * <p>
       * This method uses {@link Collections#sort(List, Comparator)}
       * and returns the original list.
       *
       * @param files The files to sort, may be null
       * @return The sorted list
       * @since Commons IO 2.0
       */
      public List<File> sort(List<File> files) {
          if (files != null) {
              Collections.sort(files, this);
          }
          return files;
      }
  
      /**
       * String representation of this file comparator.
       *
       * @return String representation of this file comparator
       */
      @Override
      public String toString() {
          return getClass().getSimpleName();
      }
  }
  