/*
* Copyright 2003-2006 The Apache Software Foundation
*
* Licensed 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.qpid.collections.keyvalue;
import java.util.Map;
import org.apache.qpid.collections.keyvalue.AbstractKeyValue;
/**
* Abstract Pair class to assist with creating correct
* {@link java.util.Map.Entry Map.Entry} implementations.
*
* @since Commons Collections 3.0
* @version $Revision$ $Date$
*
* @author James Strachan
* @author Michael A. Smith
* @author Neil O'Toole
* @author Stephen Colebourne
*/
public abstract class AbstractMapEntry extends AbstractKeyValue implements Map.Entry {
/**
* Constructs a new entry with the given key and given value.
*
* @param key the key for the entry, may be null
* @param value the value for the entry, may be null
*/
protected AbstractMapEntry(Object key, Object value) {
super(key, value);
}
// Map.Entry interface
//-------------------------------------------------------------------------
/**
* Sets the value stored in this Map.Entry
.
*
* This Map.Entry
is not connected to a Map, so only the
* local data is changed.
*
* @param value the new value
* @return the previous value
*/
public Object setValue(Object value) {
Object answer = this.value;
this.value = value;
return answer;
}
/**
* 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 */ public boolean equals(Object obj) { if (obj == this) { return true; } if (obj instanceof Map.Entry == false) { return false; } Map.Entry other = (Map.Entry) 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()} * * @return a suitable hash code */ public int hashCode() { return (getKey() == null ? 0 : getKey().hashCode()) ^ (getValue() == null ? 0 : getValue().hashCode()); } }