| /* |
| * 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.math4.legacy.core; |
| |
| /** |
| * Generic pair. |
| * <br> |
| * Although the instances of this class are immutable, it is impossible |
| * to ensure that the references passed to the constructor will not be |
| * modified by the caller. |
| * |
| * @param <K> Key type. |
| * @param <V> Value type. |
| * |
| * @since 3.0 |
| */ |
| public class Pair<K, V> { |
| /** Key. */ |
| private final K key; |
| /** Value. */ |
| private final V value; |
| |
| /** |
| * Create an entry representing a mapping from the specified key to the |
| * specified value. |
| * |
| * @param k Key (first element of the pair). |
| * @param v Value (second element of the pair). |
| */ |
| public Pair(K k, V v) { |
| key = k; |
| value = v; |
| } |
| |
| /** |
| * Create an entry representing the same mapping as the specified entry. |
| * |
| * @param entry Entry to copy. |
| */ |
| public Pair(Pair<? extends K, ? extends V> entry) { |
| this(entry.getKey(), entry.getValue()); |
| } |
| |
| /** |
| * Get the key. |
| * |
| * @return the key (first element of the pair). |
| */ |
| public K getKey() { |
| return getFirst(); |
| } |
| |
| /** |
| * Get the value. |
| * |
| * @return the value (second element of the pair). |
| */ |
| public V getValue() { |
| return getSecond(); |
| } |
| |
| /** |
| * Get the first element of the pair. |
| * |
| * @return the first element of the pair. |
| * @since 3.1 |
| */ |
| public K getFirst() { |
| return key; |
| } |
| |
| /** |
| * Get the second element of the pair. |
| * |
| * @return the second element of the pair. |
| * @since 3.1 |
| */ |
| public V getSecond() { |
| return value; |
| } |
| |
| /** |
| * Compare the specified object with this entry for equality. |
| * |
| * @param o Object. |
| * @return {@code true} if the given object is also a map entry and |
| * the two entries represent the same mapping. |
| */ |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (!(o instanceof Pair)) { |
| return false; |
| } else { |
| Pair<?, ?> oP = (Pair<?, ?>) o; |
| return (key == null ? |
| oP.key == null : |
| key.equals(oP.key)) && |
| (value == null ? |
| oP.value == null : |
| value.equals(oP.value)); |
| } |
| } |
| |
| /** |
| * Compute a hash code. |
| * |
| * @return the hash code value. |
| */ |
| @Override |
| public int hashCode() { |
| int result = key == null ? 0 : key.hashCode(); |
| |
| final int h = value == null ? 0 : value.hashCode(); |
| result = 37 * result + h ^ (h >>> 16); |
| |
| return result; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public String toString() { |
| return "[" + getKey() + ", " + getValue() + "]"; |
| } |
| |
| /** |
| * Convenience factory method that calls the |
| * {@link #Pair(Object, Object) constructor}. |
| * |
| * @param <K> the key type |
| * @param <V> the value type |
| * @param k First element of the pair. |
| * @param v Second element of the pair. |
| * @return a new {@code Pair} containing {@code k} and {@code v}. |
| * @since 3.3 |
| */ |
| public static <K, V> Pair<K, V> create(K k, V v) { |
| return new Pair<>(k, v); |
| } |
| } |