org.apache.commons.collections4.keyvalue.TiedMapEntry Maven / Gradle / Ivy
/*
* 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.collections4.keyvalue;
import java.io.Serializable;
import java.util.Map;
import org.apache.commons.collections4.KeyValue;
/**
* A {@link java.util.Map.Entry Map.Entry} tied to a map underneath.
*
* This can be used to enable a map entry to make changes on the underlying
* map, however this will probably mess up any iterators.
*
* @since 3.0
*/
public class TiedMapEntry implements Map.Entry, KeyValue, Serializable {
/** Serialization version */
private static final long serialVersionUID = -8453869361373831205L;
/** The map underlying the entry/iterator */
private final Map map;
/** The key */
private final K key;
/**
* Constructs a new entry with the given Map and key.
*
* @param map the map
* @param key the key
*/
public TiedMapEntry(final Map map, final K key) {
super();
this.map = map;
this.key = key;
}
// Map.Entry interface
//-------------------------------------------------------------------------
/**
* Gets the key of this entry
*
* @return the key
*/
@Override
public K getKey() {
return key;
}
/**
* Gets the value of this entry direct from the map.
*
* @return the value
*/
@Override
public V getValue() {
return map.get(key);
}
/**
* Sets the value associated with the key direct onto the map.
*
* @param value the new value
* @return the old value
* @throws IllegalArgumentException if the value is set to this map entry
*/
@Override
public V setValue(final V value) {
if (value == this) {
throw new IllegalArgumentException("Cannot set value to this map entry");
}
return map.put(key, value);
}
/**
* Compares this Map.Entry with another Map.Entry.
*
* Implemented per API documentation of {@link java.util.Map.Entry#equals(Object)}
*
* @param obj the object to compare to
* @return true if equal key and value
*/
@Override
public boolean equals(final Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof Map.Entry == false) {
return false;
}
final Map.Entry other = (Map.Entry) obj;
final Object value = getValue();
return
(key == null ? other.getKey() == null : key.equals(other.getKey())) &&
(value == null ? other.getValue() == null : value.equals(other.getValue()));
}
/**
* Gets a hashCode compatible with the equals method.
*
* Implemented per API documentation of {@link java.util.Map.Entry#hashCode()}
*
* @return a suitable hash code
*/
@Override
public int hashCode() {
final Object value = getValue();
return (getKey() == null ? 0 : getKey().hashCode()) ^
(value == null ? 0 : value.hashCode());
}
/**
* Gets a string version of the entry.
*
* @return entry as a string
*/
@Override
public String toString() {
return getKey() + "=" + getValue();
}
}