    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
    018package org.apache.commons.lang3.mutable;
    019
    020/**
    021 * Provides mutable access to a value.
    022 * <p>
    023 * {@link Mutable} is used as a generic interface to the implementations in this package.
    024 * </p>
    025 * <p>
    026 * A typical use case would be to enable a primitive or string to be passed to a method and allow that method to
    027 * effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in
    028 * a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.
    029 * </p>
    030 *
    031 * @param <T> the type to set and get
    032 * @since 2.1
    033 */
    034public 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}