org.apache.felix.eventadmin/src/main/java/org/apache/felix/eventadmin/impl/util/CacheMap.java

/*
 *   Copyright 2005 The Apache Software Foundation
 *
 *   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 org.apache.felix.eventadmin.impl.util;

/**
 * This is the interface of a simple cache map. 
 * 
 * @author <a href="mailto:felix-dev@incubator.apache.org">Felix Project Team</a>
 */
public interface CacheMap
{
    /**
     * Return the value for the key in case there is one in the cache.
     * 
     * @param key The key to look-up
     * 
     * @return The value for the given key in case there is one in the cache, 
     *      <tt>null</tt> otherwise
     */
    public Object get(final Object key);
    
    /**
     * Add a value for the key to this cache.
     * 
     * @param key The key for the value
     * @param value The value to add to the cache 
     */
    public void add(final Object key, final Object value);
    
    /**
     * Remove a key and its value from the cache.
     * 
     * @param key The key to remove
     * 
     * @return The value of the key in case there is one in the cache, <tt>null</tt>
     *      otherwise
     */
    public Object remove(final Object key);
    
    /**
     * Returns the number of key-value pairs in this cache.
     * 
     * @return The number of key-value pairs in this cache
     */
    public int size();
    
    /**
     * Remove all entries of the cache.
     */
    public void clear();
}