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/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003-2004 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
*
* Note that a DefaultKeyValue instance may not contain
* itself as a key or value.
*
* @since Commons Collections 3.0
* @version $Revision: 1.3 $ $Date: 2004/01/14 21:43:16 $
*
* @author James Strachan
* @author Michael A. Smith
* @author Neil O'Toole
* @author Stephen Colebourne
*/
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 Object key, final Object 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 MapEntry.
*
* @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
*/
public Object setKey(final Object key) {
if (key == this) {
throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a key.");
}
final Object old = this.key;
this.key = key;
return old;
}
/**
* Sets the value.
*
* @return the old value of the value
* @param value the new value
* @throws IllegalArgumentException if value is this object
*/
public Object setValue(final Object value) {
if (value == this) {
throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a value.");
}
final Object old = this.value;
this.value = value;
return old;
}
//-----------------------------------------------------------------------
/**
* 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
*/
public boolean equals(final Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof DefaultKeyValue == false) {
return false;
}
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
*/
public int hashCode() {
return (getKey() == null ? 0 : getKey().hashCode()) ^
(getValue() == null ? 0 : getValue().hashCode());
}
}