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;
  
  import java.io.Serializable;
  
  /**
   * A mutable <code>Object</code> wrapper.
   * 
   * @since 2.1
   * @version $Id: MutableObject.java 437554 2006-08-28 06:21:41Z bayard $
   */
  public class MutableObject implements Mutable, Serializable {
  
      /**
       * Required for serialization support.
       * 
       * @see java.io.Serializable
       */
      private static final long serialVersionUID = 86241875189L;
  
      /** The mutable value. */
      private Object value;
  
      /**
       * Constructs a new MutableObject with the default value of <code>null</code>.
       */
      public MutableObject() {
          super();
      }
  
      /**
       * Constructs a new MutableObject with the specified value.
       * 
       * @param value
       *            a value.
       */
      public MutableObject(Object value) {
          super();
          this.value = value;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets the value.
       * 
       * @return the value
       */
      public Object getValue() {
          return this.value;
      }
  
      /**
       * Sets the value.
       * 
       * @param value
       *            the value to set
       */
      public void setValue(Object value) {
          this.value = value;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Compares this object against the specified object. The result is <code>true</code> if and only if the argument
       * is not <code>null</code> and is a <code>MutableObject</code> object that contains the same <code>Object</code>
       * value as this object.
       * 
       * @param obj
       *            the object to compare with.
       * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
       */
      public boolean equals(Object obj) {
          if (obj instanceof MutableObject) {
              Object other = ((MutableObject) obj).value;
              return value == other || (value != null && value.equals(other));
          }
          return false;
      }
  
      /**
       * Returns the value's hash code or <code>0</code> if the value is <code>null</code>.
       * 
       * @return the value's hash code or <code>0</code> if the value is <code>null</code>.
       */
      public int hashCode() {
          return value == null ? 0 : value.hashCode();
      }
  
      /**
       * Returns the String value of this mutable.
       * 
       * @return the mutable value as a string
       */
      public String toString() {
          return value == null ? "null" : value.toString();
      }
  
  }
  