    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4.keyvalue;
    018
    019import java.util.Map.Entry;
    020
    021import org.apache.commons.collections4.KeyValue;
    022/**
    023 * Abstract pair class to assist with creating {@code KeyValue}
    024 * and {@link Entry Map.Entry} implementations.
    025 *
    026 * @param <K> The type of keys
    027 * @param <V> The type of values
    028 * @since 3.0
    029 */
    030public abstract class AbstractKeyValue<K, V> implements KeyValue<K, V> {
    031
    032    /** The key */
    033    private K key;
    034
    035    /** The value */
    036    private V value;
    037
    038    /**
    039     * Constructs a new pair with the specified key and given value.
    040     *
    041     * @param key  The key for the entry, may be null
    042     * @param value  The value for the entry, may be null
    043     */
    044    protected AbstractKeyValue(final K key, final V value) {
    045        this.key = key;
    046        this.value = value;
    047    }
    048
    049    /**
    050     * Gets the key from the pair.
    051     *
    052     * @return The key
    053     */
    054    @Override
    055    public K getKey() {
    056        return key;
    057    }
    058
    059    /**
    060     * Gets the value from the pair.
    061     *
    062     * @return The value
    063     */
    064    @Override
    065    public V getValue() {
    066        return value;
    067    }
    068
    069    /**
    070     * Sets the key.
    071     *
    072     * @param key The key.
    073     * @return The previous key.
    074     */
    075    protected K setKey(final K key) {
    076        final K old = this.key;
    077        this.key = key;
    078        return old;
    079    }
    080
    081    /**
    082     * Sets the value.
    083     *
    084     * @param value The value.
    085     * @return The previous value.
    086     */
    087    protected V setValue(final V value) {
    088        final V old = this.value;
    089        this.value = value;
    090        return old;
    091    }
    092
    093    /**
    094     * Gets a debugging String view of the pair.
    095     *
    096     * @return A String view of the entry
    097     */
    098    @Override
    099    public String toString() {
    100        return new StringBuilder()
    101            .append(getKey())
    102            .append('=')
    103            .append(getValue())
    104            .toString();
    105    }
    106
    107}