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.lang3.tuple;
18
19 /**
20 * <p>An immutable pair consisting of two {@code Object} elements.</p>
21 *
22 * <p>Although the implementation is immutable, there is no restriction on the objects
23 * that may be stored. If mutable objects are stored in the pair, then the pair
24 * itself effectively becomes mutable. The class is also not {@code final}, so a subclass
25 * could add undesirable behaviour.</p>
26 *
27 * <p>#ThreadSafe# if both paired objects are thread-safe</p>
28 *
29 * @param <L> the left element type
30 * @param <R> the right element type
31 *
32 * @since Lang 3.0
33 * @version $Id: ImmutablePair.java 1436768 2013-01-22 07:07:42Z ggregory $
34 */
35 public final class ImmutablePair<L, R> extends Pair<L, R> {
36
37 /** Serialization version */
38 private static final long serialVersionUID = 4954918890077093841L;
39
40 /** Left object */
41 public final L left;
42 /** Right object */
43 public final R right;
44
45 /**
46 * <p>Obtains an immutable pair of from two objects inferring the generic types.</p>
47 *
48 * <p>This factory allows the pair to be created using inference to
49 * obtain the generic types.</p>
50 *
51 * @param <L> the left element type
52 * @param <R> the right element type
53 * @param left the left element, may be null
54 * @param right the right element, may be null
55 * @return a pair formed from the two parameters, not null
56 */
57 public static <L, R> ImmutablePair<L, R> of(final L left, final R right) {
58 return new ImmutablePair<L, R>(left, right);
59 }
60
61 /**
62 * Create a new pair instance.
63 *
64 * @param left the left value, may be null
65 * @param right the right value, may be null
66 */
67 public ImmutablePair(final L left, final R right) {
68 super();
69 this.left = left;
70 this.right = right;
71 }
72
73 //-----------------------------------------------------------------------
74 /**
75 * {@inheritDoc}
76 */
77 @Override
78 public L getLeft() {
79 return left;
80 }
81
82 /**
83 * {@inheritDoc}
84 */
85 @Override
86 public R getRight() {
87 return right;
88 }
89
90 /**
91 * <p>Throws {@code UnsupportedOperationException}.</p>
92 *
93 * <p>This pair is immutable, so this operation is not supported.</p>
94 *
95 * @param value the value to set
96 * @return never
97 * @throws UnsupportedOperationException as this operation is not supported
98 */
99 @Override
100 public R setValue(final R value) {
101 throw new UnsupportedOperationException();
102 }
103
104 }