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 * @author Apache Software Foundation
027 * @version $Id: MutableObject.java 905636 2010-02-02 14:03:32Z niallp $
028 */
029 public class MutableObject implements Mutable, Serializable {
030
031 /**
032 * Required for serialization support.
033 *
034 * @see java.io.Serializable
035 */
036 private static final long serialVersionUID = 86241875189L;
037
038 /** The mutable value. */
039 private Object value;
040
041 /**
042 * Constructs a new MutableObject with the default value of <code>null</code>.
043 */
044 public MutableObject() {
045 super();
046 }
047
048 /**
049 * Constructs a new MutableObject with the specified value.
050 *
051 * @param value the initial value to store
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, may be null
063 */
064 public Object getValue() {
065 return this.value;
066 }
067
068 /**
069 * Sets the value.
070 *
071 * @param value the value to set
072 */
073 public void setValue(Object value) {
074 this.value = value;
075 }
076
077 //-----------------------------------------------------------------------
078 /**
079 * Compares this object against the specified object. The result is <code>true</code> if and only if the argument
080 * is not <code>null</code> and is a <code>MutableObject</code> object that contains the same <code>Object</code>
081 * value as this object.
082 *
083 * @param obj the object to compare with, null returns false
084 * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
085 */
086 public boolean equals(Object obj) {
087 if (obj instanceof MutableObject) {
088 Object other = ((MutableObject) obj).value;
089 return value == other || (value != null && value.equals(other));
090 }
091 return false;
092 }
093
094 /**
095 * Returns the value's hash code or <code>0</code> if the value is <code>null</code>.
096 *
097 * @return the value's hash code or <code>0</code> if the value is <code>null</code>.
098 */
099 public int hashCode() {
100 return value == null ? 0 : value.hashCode();
101 }
102
103 //-----------------------------------------------------------------------
104 /**
105 * Returns the String value of this mutable.
106 *
107 * @return the mutable value as a string
108 */
109 public String toString() {
110 return value == null ? "null" : value.toString();
111 }
112
113 }