com.ibm.icu.impl.CacheBase Maven / Gradle / Ivy
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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 2010, International Business Machines
* Corporation and others. All Rights Reserved.
*******************************************************************************
*/
package com.ibm.icu.impl;
/**
* Base class for cache implementations.
* To use, instantiate a subclass of a concrete implementation class, where the subclass
* implements the createInstance() method, and call get() with the key and the data.
* The get() call will use the data only if it needs to call createInstance(),
* otherwise the data is ignored.
*
* @param Cache lookup key type
* @param Cache instance value type
* @param Data type for creating a new instance value
*
* @author Markus Scherer, Mark Davis
*/
public abstract class CacheBase {
/**
* Retrieves an instance from the cache. Calls createInstance(key, data) if the cache
* does not already contain an instance with this key.
* Ignores data if the cache already contains an instance with this key.
* @param key Cache lookup key for the requested instance
* @param data Data for createInstance() if the instance is not already cached
* @return The requested instance
*/
public abstract V getInstance(K key, D data);
/**
* Creates an instance for the key and data. Must be overridden.
* @param key Cache lookup key for the requested instance
* @param data Data for the instance creation
* @return The requested instance
*/
protected abstract V createInstance(K key, D data);
}