KeyExtractor.java

/**
 *
 * 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.openejb.jee;

/**
 * Extracts an immutable key for this object.
 * <p/>
 * It is important for the key to not be mutable and that the key value
 * itself is not changed in the object.  If this happens any AutoIndex,
 * or Map using this key will break.
 */
public interface KeyExtractor<K, V> {
    /**
     * Gets the immutable key for the specified value.
     *
     * @return gets the immutable key for the specified value
     */
    K getKey(V value);
}