    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
    018package org.apache.commons.lang3.mutable;
    019
    020import java.io.Serializable;
    021
    022/**
    023 * A mutable {@code Object} wrapper.
    024 *
    025 * @param <T> the type to set and get
    026 * @since 2.1
    027 */
    028public 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}.
    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(final 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    @Override
    064    public T getValue() {
    065        return this.value;
    066    }
    067
    068    /**
    069     * Sets the value.
    070     *
    071     * @param value  the value to set
    072     */
    073    @Override
    074    public void setValue(final T value) {
    075        this.value = value;
    076    }
    077
    078    //-----------------------------------------------------------------------
    079    /**
    080     * <p>
    081     * Compares this object against the specified object. The result is {@code true} if and only if the argument
    082     * is not {@code null} and is a {@code MutableObject} object that contains the same {@code T}
    083     * value as this object.
    084     * </p>
    085     *
    086     * @param obj  the object to compare with, {@code null} returns {@code false}
    087     * @return  {@code true} if the objects are the same;
    088     *          {@code true} if the objects have equivalent {@code value} fields;
    089     *          {@code false} otherwise.
    090     */
    091    @Override
    092    public boolean equals(final Object obj) {
    093        if (obj == null) {
    094            return false;
    095        }
    096        if (this == obj) {
    097            return true;
    098        }
    099        if (this.getClass() == obj.getClass()) {
    100            final MutableObject<?> that = (MutableObject<?>) obj;
    101            return this.value.equals(that.value);
    102        }
    103        return false;
    104    }
    105
    106    /**
    107     * Returns the value's hash code or {@code 0} if the value is {@code null}.
    108     *
    109     * @return the value's hash code or {@code 0} if the value is {@code null}.
    110     */
    111    @Override
    112    public int hashCode() {
    113        return value == null ? 0 : value.hashCode();
    114    }
    115
    116    //-----------------------------------------------------------------------
    117    /**
    118     * Returns the String value of this mutable.
    119     *
    120     * @return the mutable value as a string
    121     */
    122    @Override
    123    public String toString() {
    124        return value == null ? "null" : value.toString();
    125    }
    126
    127}