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.functor.core.comparator;
18
19 import java.util.Comparator;
20
21 /**
22 * A {@link Comparator Comparator} that compares {@link Comparable Comparable}
23 * objects.
24 * <p>
25 * This class was created based on commons-collection's ComparableComparator.
26 *
27 * @param <E> the comparable type
28 * @version $Revision: 1537901 $ $Date: 2013-11-01 12:30:19 +0100 (Fr, 01 Nov 2013) $
29 */
30 final class ComparableComparator<E extends Comparable<? super E>> implements Comparator<E> {
31
32 /** Singleton. */
33 @SuppressWarnings("rawtypes")
34 public static final ComparableComparator<?> INSTANCE = new ComparableComparator();
35
36 /**
37 * Create a new ComparableComparator.
38 */
39 public ComparableComparator() {
40 super();
41 }
42
43 /**
44 * {@inheritDoc}
45 */
46 public int compare(E o1, E o2) {
47 return o1.compareTo(o2);
48 }
49
50 /**
51 * {@inheritDoc}
52 */
53 @Override
54 public boolean equals(Object obj) {
55 return (obj instanceof ComparableComparator);
56 }
57
58 /**
59 * {@inheritDoc}
60 */
61 @Override
62 public int hashCode() {
63 return toString().hashCode();
64 }
65
66 /**
67 * {@inheritDoc}
68 */
69 @Override
70 public String toString() {
71 return "ComparableComparator";
72 }
73
74 /**
75 * Get a ComparableComparator instance.
76 * @param <E> the comparable type
77 * @return ComparableComparator
78 */
79 @SuppressWarnings("unchecked")
80 public static <E extends Comparable<? super E>> ComparableComparator<E> instance() {
81 return (ComparableComparator<E>) INSTANCE;
82 }
83
84 }