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 */ 017package org.apache.commons.collections4.keyvalue; 018 019import java.util.Map; 020 021/** 022 * Abstract Pair class to assist with creating correct 023 * {@link java.util.Map.Entry Map.Entry} implementations. 024 * 025 * @param <K> the type of keys 026 * @param <V> the type of mapped values 027 * @since 3.0 028 */ 029public abstract class AbstractMapEntry<K, V> extends AbstractKeyValue<K, V> implements Map.Entry<K, V> { 030 031 /** 032 * Constructs a new entry with the given key and given value. 033 * 034 * @param key the key for the entry, may be null 035 * @param value the value for the entry, may be null 036 */ 037 protected AbstractMapEntry(final K key, final V value) { 038 super(key, value); 039 } 040 041 /** 042 * Compares this {@code Map.Entry} with another {@code Map.Entry}. 043 * <p> 044 * Implemented per API documentation of {@link java.util.Map.Entry#equals(Object)} 045 * 046 * @param obj the object to compare to 047 * @return true if equal key and value 048 */ 049 @Override 050 public boolean equals(final Object obj) { 051 if (obj == this) { 052 return true; 053 } 054 if (!(obj instanceof Map.Entry)) { 055 return false; 056 } 057 final Map.Entry<?, ?> other = (Map.Entry<?, ?>) obj; 058 return 059 (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey())) && 060 (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue())); 061 } 062 063 /** 064 * Gets a hashCode compatible with the equals method. 065 * <p> 066 * Implemented per API documentation of {@link java.util.Map.Entry#hashCode()} 067 * 068 * @return a suitable hash code 069 */ 070 @Override 071 public int hashCode() { 072 return (getKey() == null ? 0 : getKey().hashCode()) ^ 073 (getValue() == null ? 0 : getValue().hashCode()); 074 } 075 076 /** 077 * Sets the value stored in this {@code Map.Entry}. 078 * <p> 079 * This {@code Map.Entry} is not connected to a Map, so only the 080 * local data is changed. 081 * 082 * @param value the new value 083 * @return the previous value 084 */ 085 @Override 086 public V setValue(final V value) { // NOPMD 087 return super.setValue(value); 088 } 089 090}