| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.lang3.tuple; |
| |
| import java.util.Map; |
| |
| /** |
| * <p>An immutable pair consisting of two {@code Object} elements.</p> |
| * |
| * <p>Although the implementation is immutable, there is no restriction on the objects |
| * that may be stored. If mutable objects are stored in the pair, then the pair |
| * itself effectively becomes mutable. The class is also {@code final}, so a subclass |
| * can not add undesirable behavior.</p> |
| * |
| * <p>#ThreadSafe# if both paired objects are thread-safe</p> |
| * |
| * @param <L> the left element type |
| * @param <R> the right element type |
| * |
| * @since 3.0 |
| */ |
| public final class ImmutablePair<L, R> extends Pair<L, R> { |
| |
| /** |
| * An empty array. |
| * <p> |
| * Consider using {@link #emptyArray()} to avoid generics warnings. |
| * </p> |
| * |
| * @since 3.10. |
| */ |
| public static final ImmutablePair<?, ?>[] EMPTY_ARRAY = new ImmutablePair[0]; |
| |
| /** |
| * An immutable pair of nulls. |
| */ |
| // This is not defined with generics to avoid warnings in call sites. |
| @SuppressWarnings("rawtypes") |
| private static final ImmutablePair NULL = of(null, null); |
| |
| /** Serialization version */ |
| private static final long serialVersionUID = 4954918890077093841L; |
| |
| /** |
| * Returns the empty array singleton that can be assigned without compiler warning. |
| * |
| * @param <L> the left element type |
| * @param <R> the right element type |
| * @return the empty array singleton that can be assigned without compiler warning. |
| * |
| * @since 3.10. |
| */ |
| @SuppressWarnings("unchecked") |
| public static <L, R> ImmutablePair<L, R>[] emptyArray() { |
| return (ImmutablePair<L, R>[]) EMPTY_ARRAY; |
| } |
| |
| /** |
| * <p>Creates an immutable pair of two objects inferring the generic types.</p> |
| * |
| * <p>This factory allows the pair to be created using inference to |
| * obtain the generic types.</p> |
| * |
| * @param <L> the left element type |
| * @param <R> the right element type |
| * @param left the left element, may be null |
| * @return a pair formed from the two parameters, not null |
| * @since 3.11 |
| */ |
| public static <L, R> Pair<L, R> left(final L left) { |
| return ImmutablePair.of(left, null); |
| } |
| |
| /** |
| * Returns an immutable pair of nulls. |
| * |
| * @param <L> the left element of this pair. Value is {@code null}. |
| * @param <R> the right element of this pair. Value is {@code null}. |
| * @return an immutable pair of nulls. |
| * @since 3.6 |
| */ |
| public static <L, R> ImmutablePair<L, R> nullPair() { |
| return NULL; |
| } |
| |
| /** |
| * <p>Creates an immutable pair of two objects inferring the generic types.</p> |
| * |
| * <p>This factory allows the pair to be created using inference to |
| * obtain the generic types.</p> |
| * |
| * @param <L> the left element type |
| * @param <R> the right element type |
| * @param left the left element, may be null |
| * @param right the right element, may be null |
| * @return a pair formed from the two parameters, not null |
| */ |
| public static <L, R> ImmutablePair<L, R> of(final L left, final R right) { |
| return new ImmutablePair<>(left, right); |
| } |
| |
| /** |
| * <p>Creates an immutable pair from an existing pair.</p> |
| * |
| * <p>This factory allows the pair to be created using inference to |
| * obtain the generic types.</p> |
| * |
| * @param <L> the left element type |
| * @param <R> the right element type |
| * @param pair the existing pair. |
| * @return a pair formed from the two parameters, not null |
| * @since 3.10 |
| */ |
| public static <L, R> ImmutablePair<L, R> of(final Map.Entry<L, R> pair) { |
| final L left; |
| final R right; |
| if (pair != null) { |
| left = pair.getKey(); |
| right = pair.getValue(); |
| } else { |
| left = null; |
| right = null; |
| } |
| return new ImmutablePair<>(left, right); |
| } |
| |
| /** |
| * <p>Creates an immutable pair of two objects inferring the generic types.</p> |
| * |
| * <p>This factory allows the pair to be created using inference to |
| * obtain the generic types.</p> |
| * |
| * @param <L> the left element type |
| * @param <R> the right element type |
| * @param right the right element, may be null |
| * @return a pair formed from the two parameters, not null |
| * @since 3.11 |
| */ |
| public static <L, R> Pair<L, R> right(final R right) { |
| return ImmutablePair.of(null, right); |
| } |
| |
| /** Left object */ |
| public final L left; |
| |
| /** Right object */ |
| public final R right; |
| |
| /** |
| * Create a new pair instance. |
| * |
| * @param left the left value, may be null |
| * @param right the right value, may be null |
| */ |
| public ImmutablePair(final L left, final R right) { |
| this.left = left; |
| this.right = right; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public L getLeft() { |
| return left; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public R getRight() { |
| return right; |
| } |
| |
| /** |
| * <p>Throws {@code UnsupportedOperationException}.</p> |
| * |
| * <p>This pair is immutable, so this operation is not supported.</p> |
| * |
| * @param value the value to set |
| * @return never |
| * @throws UnsupportedOperationException as this operation is not supported |
| */ |
| @Override |
| public R setValue(final R value) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| } |