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.lang.mutable;
019
020 import java.io.Serializable;
021
022 /**
023 * A mutable <code>Object</code> wrapper.
024 *
025 * @since 2.1
026 * @version $Id: MutableObject.java 437554 2006-08-28 06:21:41Z bayard $
027 */
028 public class MutableObject implements Mutable, Serializable {
029
030 /**
031 * Required for serialization support.
032 *
033 * @see java.io.Serializable
034 */
035 private static final long serialVersionUID = 86241875189L;
036
037 /** The mutable value. */
038 private Object value;
039
040 /**
041 * Constructs a new MutableObject with the default value of <code>null</code>.
042 */
043 public MutableObject() {
044 super();
045 }
046
047 /**
048 * Constructs a new MutableObject with the specified value.
049 *
050 * @param value
051 * a value.
052 */
053 public MutableObject(Object value) {
054 super();
055 this.value = value;
056 }
057
058 //-----------------------------------------------------------------------
059 /**
060 * Gets the value.
061 *
062 * @return the value
063 */
064 public Object getValue() {
065 return this.value;
066 }
067
068 /**
069 * Sets the value.
070 *
071 * @param value
072 * the value to set
073 */
074 public void setValue(Object value) {
075 this.value = value;
076 }
077
078 //-----------------------------------------------------------------------
079 /**
080 * Compares this object against the specified object. The result is <code>true</code> if and only if the argument
081 * is not <code>null</code> and is a <code>MutableObject</code> object that contains the same <code>Object</code>
082 * value as this object.
083 *
084 * @param obj
085 * the object to compare with.
086 * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
087 */
088 public boolean equals(Object obj) {
089 if (obj instanceof MutableObject) {
090 Object other = ((MutableObject) obj).value;
091 return value == other || (value != null && value.equals(other));
092 }
093 return false;
094 }
095
096 /**
097 * Returns the value's hash code or <code>0</code> if the value is <code>null</code>.
098 *
099 * @return the value's hash code or <code>0</code> if the value is <code>null</code>.
100 */
101 public int hashCode() {
102 return value == null ? 0 : value.hashCode();
103 }
104
105 /**
106 * Returns the String value of this mutable.
107 *
108 * @return the mutable value as a string
109 */
110 public String toString() {
111 return value == null ? "null" : value.toString();
112 }
113
114 }