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.lang3.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 1088899 2011-04-05 05:31:27Z bayard $
027 */
028 public class MutableObject<T> implements Mutable<T>, 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 T 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 the initial value to store
051 */
052 public MutableObject(T value) {
053 super();
054 this.value = value;
055 }
056
057 //-----------------------------------------------------------------------
058 /**
059 * Gets the value.
060 *
061 * @return the value, may be null
062 */
063 public T getValue() {
064 return this.value;
065 }
066
067 /**
068 * Sets the value.
069 *
070 * @param value the value to set
071 */
072 public void setValue(T value) {
073 this.value = value;
074 }
075
076 //-----------------------------------------------------------------------
077 /**
078 * <p>
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>T</code>
081 * value as this object.
082 * </p>
083 *
084 * @param obj the object to compare with, <code>null</code> returns <code>false</code>
085 * @return <code>true</code> if the objects are the same;
086 * <code>true</code> if the objects have equivalent <code>value</code> fields;
087 * <code>false</code> otherwise.
088 */
089 @Override
090 public boolean equals(Object obj) {
091 if (obj == null) {
092 return false;
093 }
094 if (this == obj) {
095 return true;
096 }
097 if (this.getClass() == obj.getClass()) {
098 MutableObject<?> that = (MutableObject<?>) obj;
099 return this.value.equals(that.value);
100 } else {
101 return false;
102 }
103 }
104
105 /**
106 * Returns the value's hash code or <code>0</code> if the value is <code>null</code>.
107 *
108 * @return the value's hash code or <code>0</code> if the value is <code>null</code>.
109 */
110 @Override
111 public int hashCode() {
112 return value == null ? 0 : value.hashCode();
113 }
114
115 //-----------------------------------------------------------------------
116 /**
117 * Returns the String value of this mutable.
118 *
119 * @return the mutable value as a string
120 */
121 @Override
122 public String toString() {
123 return value == null ? "null" : value.toString();
124 }
125
126 }