    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    }