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/*
 * 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.util.Map;

import org.apache.commons.collections4.KeyValue;

/**
 * A mutable KeyValue pair that does not implement
 * {@link java.util.Map.Entry Map.Entry}.
 * 

* Note that a DefaultKeyValue instance may not contain * itself as a key or value. * * @since 3.0 * @version $Id: DefaultKeyValue.java 1533984 2013-10-20 21:12:51Z tn $ */ public class DefaultKeyValue extends AbstractKeyValue { /** * Constructs a new pair with a null key and null value. */ public DefaultKeyValue() { super(null, null); } /** * Constructs a new pair with the specified key and given value. * * @param key the key for the entry, may be null * @param value the value for the entry, may be null */ public DefaultKeyValue(final K key, final V value) { super(key, value); } /** * Constructs a new pair from the specified KeyValue. * * @param pair the pair to copy, must not be null * @throws NullPointerException if the entry is null */ public DefaultKeyValue(final KeyValue pair) { super(pair.getKey(), pair.getValue()); } /** * Constructs a new pair from the specified Map.Entry. * * @param entry the entry to copy, must not be null * @throws NullPointerException if the entry is null */ public DefaultKeyValue(final Map.Entry entry) { super(entry.getKey(), entry.getValue()); } //----------------------------------------------------------------------- /** * Sets the key. * * @param key the new key * @return the old key * @throws IllegalArgumentException if key is this object */ @Override public K setKey(final K key) { if (key == this) { throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a key."); } return super.setKey(key); } /** * Sets the value. * * @return the old value of the value * @param value the new value * @throws IllegalArgumentException if value is this object */ @Override public V setValue(final V value) { if (value == this) { throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a value."); } return super.setValue(value); } //----------------------------------------------------------------------- /** * Returns a new Map.Entry object with key and value from this pair. * * @return a MapEntry instance */ public Map.Entry toMapEntry() { return new DefaultMapEntry(this); } //----------------------------------------------------------------------- /** * Compares this Map.Entry with another Map.Entry. *

* Returns true if the compared object is also a DefaultKeyValue, * and its key and value are equal to this object's key and value. * * @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 DefaultKeyValue == false) { return false; } final DefaultKeyValue other = (DefaultKeyValue) obj; return (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey())) && (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue())); } /** * Gets a hashCode compatible with the equals method. *

* Implemented per API documentation of {@link java.util.Map.Entry#hashCode()}, * however subclasses may override this. * * @return a suitable hash code */ @Override public int hashCode() { return (getKey() == null ? 0 : getKey().hashCode()) ^ (getValue() == null ? 0 : getValue().hashCode()); } }





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