    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017
    018    package org.apache.commons.lang3.mutable;
    019
    020    /**
    021     * Provides mutable access to a value.
    022     * <p>
    023     * <code>Mutable</code> is used as a generic interface to the implementations in this package.
    024     * <p>
    025     * A typical use case would be to enable a primitive or string to be passed to a method and allow that method to
    026     * effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in
    027     * a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.
    028     *
    029     * @author Apache Software Foundation
    030     * @author Matthew Hawthorne
    031     * @since 2.1
    032     * @version $Id: Mutable.java 889215 2009-12-10 11:56:38Z bayard $
    033     */
    034    public interface Mutable<T> {
    035
    036        /**
    037         * Gets the value of this mutable.
    038         *
    039         * @return the stored value
    040         */
    041        T getValue();
    042
    043        /**
    044         * Sets the value of this mutable.
    045         *
    046         * @param value
    047         *            the value to store
    048         * @throws NullPointerException
    049         *             if the object is null and null is invalid
    050         * @throws ClassCastException
    051         *             if the type is invalid
    052         */
    053        void setValue(T value);
    054
    055    }