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;
021import java.util.Objects;
022
023/**
024 * A mutable {@link Object} wrapper.
025 *
026 * @param <T> the type to set and get
027 * @since 2.1
028 */
029public class MutableObject<T> implements Mutable<T>, 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 T value;
040
041    /**
042     * Constructs a new MutableObject with the default value of {@code null}.
043     */
044    public MutableObject() {
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        this.value = value;
054    }
055
056    /**
057     * Gets the value.
058     *
059     * @return the value, may be null
060     */
061    @Override
062    public T getValue() {
063        return this.value;
064    }
065
066    /**
067     * Sets the value.
068     *
069     * @param value  the value to set
070     */
071    @Override
072    public void setValue(final T value) {
073        this.value = value;
074    }
075
076    /**
077     * Compares this object against the specified object. The result is {@code true} if and only if the argument
078     * is not {@code null} and is a {@link MutableObject} object that contains the same {@link T}
079     * value as this object.
080     *
081     * @param obj  the object to compare with, {@code null} returns {@code false}
082     * @return  {@code true} if the objects are the same;
083     *          {@code true} if the objects have equivalent {@code value} fields;
084     *          {@code false} otherwise.
085     */
086    @Override
087    public boolean equals(final Object obj) {
088        if (obj == null) {
089            return false;
090        }
091        if (this == obj) {
092            return true;
093        }
094        if (this.getClass() == obj.getClass()) {
095            final MutableObject<?> that = (MutableObject<?>) obj;
096            return Objects.equals(this.value, that.value);
097        }
098        return false;
099    }
100
101    /**
102     * Returns the value's hash code or {@code 0} if the value is {@code null}.
103     *
104     * @return the value's hash code or {@code 0} if the value is {@code null}.
105     */
106    @Override
107    public int hashCode() {
108        return Objects.hashCode(value);
109    }
110
111    /**
112     * Returns the String value of this mutable.
113     *
114     * @return the mutable value as a string
115     */
116    @Override
117    public String toString() {
118        return Objects.toString(value);
119    }
120
121}