code: /*
   * 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.commons.lang.mutable;
  
  /**
   * Provides mutable access to a value.
   * <p>
   * <code>Mutable</code> is used as a generic interface to the implementations in this package.
   * <p>
   * A typical use case would be to enable a primitive or string to be passed to a method and allow that method to
   * effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in
   * a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.
   * 
   * @author Matthew Hawthorne
   * @since 2.1
   * @version $Id: Mutable.java 437554 2006-08-28 06:21:41Z bayard $
   */
  public interface Mutable {
  
      /**
       * Gets the value of this mutable.
       * 
       * @return the stored value
       */
      Object getValue();
  
      /**
       * Sets the value of this mutable.
       * 
       * @param value
       *            the value to store
       * @throws NullPointerException
       *             if the object is null and null is invalid
       * @throws ClassCastException
       *             if the type is invalid
       */
      void setValue(Object value);
  
  }
  