1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.io.comparator;
18
19 import java.io.File;
20 import java.io.Serializable;
21 import java.util.Comparator;
22 import java.util.Objects;
23
24 /**
25 * Reverses the result of comparing two {@link File} objects using the delegate {@link Comparator}.
26 * <h2>Deprecating Serialization</h2>
27 * <p>
28 * <em>Serialization is deprecated and will be removed in 3.0.</em>
29 * </p>
30 *
31 * @since 1.4
32 */
33 final class ReverseFileComparator extends AbstractFileComparator implements Serializable {
34
35 private static final long serialVersionUID = -4808255005272229056L;
36 private final Comparator<File> delegate;
37
38 /**
39 * Constructs an instance with the specified delegate {@link Comparator}.
40 *
41 * @param delegate The comparator to delegate to.
42 */
43 ReverseFileComparator(final Comparator<File> delegate) {
44 this.delegate = Objects.requireNonNull(delegate, "delegate");
45 }
46
47 /**
48 * Compares using the delegate Comparator, reversing the result.
49 *
50 * @param file1 The first file to compare.
51 * @param file2 The second file to compare.
52 * @return the result from the delegate {@link Comparator#compare(Object, Object)} reversing the value,
53 * positive becomes negative and vice versa.
54 */
55 @Override
56 public int compare(final File file1, final File file2) {
57 return delegate.compare(file2, file1); // parameters switched round
58 }
59
60 /**
61 * Returns the String representation of this file comparator.
62 *
63 * @return String representation of this file comparator.
64 */
65 @Override
66 public String toString() {
67 return super.toString() + "[" + delegate.toString() + "]";
68 }
69
70 }