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.ArrayList;
  import java.util.Comparator;
  import java.util.List;
  
  /**
   * Compare two files using a set of delegate file {@link Comparator}.
   * <p>
   * This comparator can be used to sort lists or arrays of files
   * by combining a number other comparators.
   * <p>
   * Example of sorting a list of files by type (i.e. directory or file)
   * and then by name:
   * <pre>
   *       CompositeFileComparator comparator =
   *                       new CompositeFileComparator(
   *                                   DirectoryFileComparator.DIRECTORY_COMPARATOR,
   *                                   NameFileComparator.NAME_COMPARATOR);
   *       List&lt;File&gt; list = ...
   *       comparator.sort(list);
   * </pre>
   *
   * @version $Revision: 1.1.2.1 $ $Date: 2011/01/15 20:32:25 $
   * @since Commons IO 2.0
   */
  public class CompositeFileComparator extends AbstractFileComparator implements Serializable {
  
      private static final Comparator<?>[] NO_COMPARATORS = {};
      private final Comparator<File>[] delegates;
  
      /**
       * Create a composite comparator for the set of delegate comparators.
       *
       * @param delegates The delegate file comparators
       */
      @SuppressWarnings("unchecked") // casts 1 & 2 must be OK because types are already correct
      public CompositeFileComparator(Comparator<File>... delegates) {
          if (delegates == null) {
              this.delegates = (Comparator<File>[]) NO_COMPARATORS;//1
          } else {
              this.delegates = (Comparator<File>[]) new Comparator<?>[delegates.length];//2
              System.arraycopy(delegates, 0, this.delegates, 0, delegates.length);
          }
      }
  
      /**
       * Create a composite comparator for the set of delegate comparators.
       *
       * @param delegates The delegate file comparators
       */
      @SuppressWarnings("unchecked") // casts 1 & 2 must be OK because types are already correct
      public CompositeFileComparator(Iterable<Comparator<File>> delegates) {
          if (delegates == null) {
              this.delegates = (Comparator<File>[]) NO_COMPARATORS; //1
          } else {
              List<Comparator<File>> list = new ArrayList<Comparator<File>>();
              for (Comparator<File> comparator : delegates) {
                  list.add(comparator);
              }
              this.delegates = (Comparator<File>[]) list.toArray(new Comparator<?>[list.size()]); //2
          }
      }
  
      /**
       * Compare the two files using delegate comparators.
       * 
       * @param file1 The first file to compare
       * @param file2 The second file to compare
       * @return the first non-zero result returned from
       * the delegate comparators or zero.
       */
      public int compare(File file1, File file2) {
          int result = 0;
          for (Comparator<File> delegate : delegates) {
              result = delegate.compare(file1, file2);
              if (result != 0) {
                  break;
              }
          }
          return result;
      }
  
      /**
       * String representation of this file comparator.
       *
       * @return String representation of this file comparator
       */
      @Override
      public String toString() {
          StringBuilder builder = new StringBuilder();
          builder.append(super.toString());
          builder.append('{');
          for (int i = 0; i < delegates.length; i++) {
              if (i > 0) {
                  builder.append(',');
              }
              builder.append(delegates[i]);
          }
          builder.append('}');
          return builder.toString();
      }
  }
  