001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.lang3.tuple;
018
019 /**
020 * <p>An immutable pair consisting of two {@code Object} elements.</p>
021 *
022 * <p>Although the implementation is immutable, there is no restriction on the objects
023 * that may be stored. If mutable objects are stored in the pair, then the pair
024 * itself effectively becomes mutable. The class is also not {@code final}, so a subclass
025 * could add undesirable behaviour.</p>
026 *
027 * <p>#ThreadSafe# if the objects are threadsafe</p>
028 *
029 * @param <L> the left element type
030 * @param <R> the right element type
031 *
032 * @since Lang 3.0
033 * @version $Id: ImmutablePair.java 1127544 2011-05-25 14:35:42Z scolebourne $
034 */
035 public final class ImmutablePair<L, R> extends Pair<L, R> {
036
037 /** Serialization version */
038 private static final long serialVersionUID = 4954918890077093841L;
039
040 /** Left object */
041 public final L left;
042 /** Right object */
043 public final R right;
044
045 /**
046 * <p>Obtains an immutable pair of from two objects inferring the generic types.</p>
047 *
048 * <p>This factory allows the pair to be created using inference to
049 * obtain the generic types.</p>
050 *
051 * @param <L> the left element type
052 * @param <R> the right element type
053 * @param left the left element, may be null
054 * @param right the right element, may be null
055 * @return a pair formed from the two parameters, not null
056 */
057 public static <L, R> ImmutablePair<L, R> of(L left, R right) {
058 return new ImmutablePair<L, R>(left, right);
059 }
060
061 /**
062 * Create a new pair instance.
063 *
064 * @param left the left value, may be null
065 * @param right the right value, may be null
066 */
067 public ImmutablePair(L left, R right) {
068 super();
069 this.left = left;
070 this.right = right;
071 }
072
073 //-----------------------------------------------------------------------
074 /**
075 * {@inheritDoc}
076 */
077 @Override
078 public L getLeft() {
079 return left;
080 }
081
082 /**
083 * {@inheritDoc}
084 */
085 @Override
086 public R getRight() {
087 return right;
088 }
089
090 /**
091 * <p>Throws {@code UnsupportedOperationException}.</p>
092 *
093 * <p>This pair is immutable, so this operation is not supported.</p>
094 *
095 * @param value the value to set
096 * @return never
097 * @throws UnsupportedOperationException as this operation is not supported
098 */
099 public R setValue(R value) {
100 throw new UnsupportedOperationException();
101 }
102
103 }