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.io.Serializable;
  import java.util.Comparator;
  
  import org.apache.commons.io.FileUtils;
  
  /**
   * Compare the <b>length/size</b> of two files for order (see
   * {@link File#length()} and {@link FileUtils#sizeOfDirectory(File)}).
   * <p>
   * This comparator can be used to sort lists or arrays of files
   * by their length/size.
   * <p>
   * Example of sorting a list of files using the
   * {@link #SIZE_COMPARATOR} singleton instance:
   * <pre>
   *       List&lt;File&gt; list = ...
   *       SizeFileComparator.SIZE_COMPARATOR.sort(list);
   * </pre>
   * <p>
   * Example of doing a <i>reverse</i> sort of an array of files using the
   * {@link #SIZE_REVERSE} singleton instance:
   * <pre>
   *       File[] array = ...
   *       SizeFileComparator.SIZE_REVERSE.sort(array);
   * </pre>
   * <p>
   * <strong>N.B.</strong> Directories are treated as <b>zero size</b> unless
   * <code>sumDirectoryContents</code> is <code>true</code>.
   *
   * @version $Revision: 1.1.2.1.2.1 $ $Date: 2011/01/15 20:32:25 $
   * @since Commons IO 1.4
   */
  public class SizeFileComparator extends AbstractFileComparator implements Serializable {
  
      /** Size comparator instance - directories are treated as zero size */
      public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();
  
      /** Reverse size comparator instance - directories are treated as zero size */
      public static final Comparator<File> SIZE_REVERSE = new ReverseComparator(SIZE_COMPARATOR);
  
      /**
       * Size comparator instance which sums the size of a directory's contents
       * using {@link FileUtils#sizeOfDirectory(File)}
       */
      public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);
  
      /**
       * Reverse size comparator instance which sums the size of a directory's contents
       * using {@link FileUtils#sizeOfDirectory(File)}
       */
      public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseComparator(SIZE_SUMDIR_COMPARATOR);
  
      /** Whether the sum of the directory's contents should be calculated. */
      private final boolean sumDirectoryContents;
  
      /**
       * Construct a file size comparator instance (directories treated as zero size).
       */
      public SizeFileComparator() {
          this.sumDirectoryContents = false;
      }
  
      /**
       * Construct a file size comparator instance specifying whether the size of
       * the directory contents should be aggregated.
       * <p>
       * If the <code>sumDirectoryContents</code> is <code>true</code> The size of
       * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
       *
       * @param sumDirectoryContents <code>true</code> if the sum of the directoryies contents
       *  should be calculated, otherwise <code>false</code> if directories should be treated
       *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
       */
      public SizeFileComparator(boolean sumDirectoryContents) {
          this.sumDirectoryContents = sumDirectoryContents;
      }
  
      /**
       * Compare the length of two files.
       * 
       * @param file1 The first file to compare
       * @param file2 The second file to compare
       * @return a negative value if the first file's length
       * is less than the second, zero if the lengths are the
       * same and a positive value if the first files length
       * is greater than the second file.
       * 
       */
      public int compare(File file1, File file2) {
          long size1 = 0;
          if (file1.isDirectory()) {
              size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
          } else {
              size1 = file1.length();
          }
          long size2 = 0;
          if (file2.isDirectory()) {
              size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
          } else {
              size2 = file2.length();
          }
          long result = size1 - size2;
          if (result < 0) {
              return -1;
          } else if (result > 0) {
              return 1;
          } else {
              return 0;
          }
      }
  
      /**
       * String representation of this file comparator.
       *
       * @return String representation of this file comparator
       */
      @Override
      public String toString() {
          return super.toString() + "[sumDirectoryContents=" + sumDirectoryContents + "]";
      }
  }
  