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The Apache Commons Collections package contains types that extend and augment the Java Collections Framework.

There is a newer version: 4.5.0-M1

/*
 * 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;

/**
 * Provides a base decorator that allows additional functionality to be
 * added to a {@link java.util.Map.Entry Map.Entry}.
 *
 * @param  the type of keys
 * @param  the type of mapped values
 * @since 3.0
 */
public abstract class AbstractMapEntryDecorator implements Map.Entry, KeyValue {

    /** The Map.Entry to decorate */
    private final Map.Entry entry;

    /**
     * Constructor that wraps (not copies).
     *
     * @param entry  the Map.Entry to decorate, must not be null
     * @throws NullPointerException if the collection is null
     */
    public AbstractMapEntryDecorator(final Map.Entry entry) {
        if (entry == null) {
            throw new NullPointerException("Map Entry must not be null.");
        }
        this.entry = entry;
    }

    /**
     * Gets the map being decorated.
     *
     * @return the decorated map
     */
    protected Map.Entry getMapEntry() {
        return entry;
    }

    //-----------------------------------------------------------------------

    @Override
    public K getKey() {
        return entry.getKey();
    }

    @Override
    public V getValue() {
        return entry.getValue();
    }

    @Override
    public V setValue(final V object) {
        return entry.setValue(object);
    }

    @Override
    public boolean equals(final Object object) {
        if (object == this) {
            return true;
        }
        return entry.equals(object);
    }

    @Override
    public int hashCode() {
        return entry.hashCode();
    }

    @Override
    public String toString() {
        return entry.toString();
    }

}