LruCache.java

/*
 * Copyright (C) 2010 Google Inc.
 *
 * 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 com.smartandroid.sa.json;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * An implementation of the {@link Cache} interface that evict objects from the
 * cache using an LRU (least recently used) algorithm. Object start getting
 * evicted from the cache once the {@code maxCapacity} is reached.
 * 
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
final class LruCache<K, V> extends LinkedHashMap<K, V> implements Cache<K, V> {
	private static final long serialVersionUID = 1L;

	private final int maxCapacity;

	public LruCache(int maxCapacity) {
		super(maxCapacity, 0.7F, true);
		this.maxCapacity = maxCapacity;
	}

	public synchronized void addElement(K key, V value) {
		put(key, value);
	}

	public synchronized V getElement(K key) {
		return get(key);
	}

	public synchronized V removeElement(K key) {
		return remove(key);
	}

	@Override
	protected boolean removeEldestEntry(Map.Entry<K, V> entry) {
		return size() > maxCapacity;
	}
}