Coverage Summary for Class: ReverseNaturalOrdering (com.google.common.collect)

1 /*
2  * Copyright (C) 2007 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.google.common.collect;
18 
19 import static com.google.common.base.Preconditions.checkNotNull;
20 
21 import com.google.common.annotations.GwtCompatible;
22 import java.io.Serializable;
23 import java.util.Iterator;
24 
25 /** An ordering that uses the reverse of the natural order of the values. */
26 @GwtCompatible(serializable = true)
27 @SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
28 final class ReverseNaturalOrdering extends Ordering<Comparable> implements Serializable {
29   static final ReverseNaturalOrdering INSTANCE = new ReverseNaturalOrdering();
30 
31   @Override
32   public int compare(Comparable left, Comparable right) {
33     checkNotNull(left); // right null is caught later
34     if (left == right) {
35       return 0;
36     }
37 
38     return right.compareTo(left);
39   }
40 
41   @Override
42   public <S extends Comparable> Ordering<S> reverse() {
43     return Ordering.natural();
44   }
45 
46   // Override the min/max methods to "hoist" delegation outside loops
47 
48   @Override
49   public <E extends Comparable> E min(E a, E b) {
50     return NaturalOrdering.INSTANCE.max(a, b);
51   }
52 
53   @Override
54   public <E extends Comparable> E min(E a, E b, E c, E... rest) {
55     return NaturalOrdering.INSTANCE.max(a, b, c, rest);
56   }
57 
58   @Override
59   public <E extends Comparable> E min(Iterator<E> iterator) {
60     return NaturalOrdering.INSTANCE.max(iterator);
61   }
62 
63   @Override
64   public <E extends Comparable> E min(Iterable<E> iterable) {
65     return NaturalOrdering.INSTANCE.max(iterable);
66   }
67 
68   @Override
69   public <E extends Comparable> E max(E a, E b) {
70     return NaturalOrdering.INSTANCE.min(a, b);
71   }
72 
73   @Override
74   public <E extends Comparable> E max(E a, E b, E c, E... rest) {
75     return NaturalOrdering.INSTANCE.min(a, b, c, rest);
76   }
77 
78   @Override
79   public <E extends Comparable> E max(Iterator<E> iterator) {
80     return NaturalOrdering.INSTANCE.min(iterator);
81   }
82 
83   @Override
84   public <E extends Comparable> E max(Iterable<E> iterable) {
85     return NaturalOrdering.INSTANCE.min(iterable);
86   }
87 
88   // preserving singleton-ness gives equals()/hashCode() for free
89   private Object readResolve() {
90     return INSTANCE;
91   }
92 
93   @Override
94   public String toString() {
95     return "Ordering.natural().reverse()";
96   }
97 
98   private ReverseNaturalOrdering() {}
99 
100   private static final long serialVersionUID = 0;
101 }