2 *******************************************************************************
3 * Copyright (C) 2010, International Business Machines
4 * Corporation and others. All Rights Reserved.
5 *******************************************************************************
7 package com.ibm.icu.impl;
10 * Base class for cache implementations.
11 * To use, instantiate a subclass of a concrete implementation class, where the subclass
12 * implements the createInstance() method, and call get() with the key and the data.
13 * The get() call will use the data only if it needs to call createInstance(),
14 * otherwise the data is ignored.
16 * @param <K> Cache lookup key type
17 * @param <V> Cache instance value type
18 * @param <D> Data type for creating a new instance value
20 * @author Markus Scherer, Mark Davis
22 public abstract class CacheBase<K, V, D> {
24 * Retrieves an instance from the cache. Calls createInstance(key, data) if the cache
25 * does not already contain an instance with this key.
26 * Ignores data if the cache already contains an instance with this key.
27 * @param key Cache lookup key for the requested instance
28 * @param data Data for createInstance() if the instance is not already cached
29 * @return The requested instance
31 public abstract V getInstance(K key, D data);
33 * Creates an instance for the key and data. Must be overridden.
34 * @param key Cache lookup key for the requested instance
35 * @param data Data for the instance creation
36 * @return The requested instance
38 protected abstract V createInstance(K key, D data);