org.apache.wicket.util.collections.MultiMap.java Source code

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Here is the source code for org.apache.wicket.util.collections.MultiMap.java

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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.wicket.util.collections;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * A simple multimap
 * 
 * @author igor
 * @param <K>
 * @param <V>
 */
public class MultiMap<K, V> extends HashMap<K, List<V>> {
    private static final long serialVersionUID = 1L;

    /**
     * Constructor
     * 
     * @see HashMap#HashMap()
     */
    public MultiMap() {
    }

    /**
     * Constructor
     * 
     * @param initialCapacity
     * @param loadFactor
     * 
     * @see HashMap#HashMap(int, float)
     */
    public MultiMap(final int initialCapacity, final float loadFactor) {
        super(initialCapacity, loadFactor);
    }

    /**
     * Constructor
     * 
     * @param initialCapacity
     * 
     * @see HashMap#HashMap(int)
     */
    public MultiMap(final int initialCapacity) {
        super(initialCapacity);
    }

    /**
     * Constructor
     * 
     * @param m
     * 
     * @see HashMap#HashMap(Map)
     */
    public MultiMap(final Map<? extends K, ? extends List<V>> m) {
        super(m);
    }

    /**
     * Adds value to the specified key
     * 
     * @param key
     * @param value
     */
    public void addValue(final K key, final V value) {
        List<V> list = get(key);
        if (list == null) {
            list = new ArrayList<>(1);
            put(key, list);
        }
        list.add(value);
    }

    /**
     * Removes value from the specified key
     * 
     * @param key
     * @param value
     */
    public void removeValue(final K key, final V value) {
        List<V> list = get(key);
        if (list != null) {
            list.remove(value);
        }
    }

    /**
     * Replaces all existing values with the specified value. If no values exist for the key the
     * value will be added.
     * 
     * @param key
     * @param value
     */
    public void replaceValues(final K key, final V value) {
        List<V> list = get(key);
        if (list != null) {
            list.clear();
            list.add(value);
        } else {
            addValue(key, value);
        }
    }

    /**
     * Gets the first value in the value list
     * 
     * @param key
     * @return first value
     */
    public V getFirstValue(final K key) {
        List<V> list = get(key);
        if ((list != null) && !list.isEmpty()) {
            return list.get(0);
        }
        return null;
    }
}