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    }