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Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang. The code is tested using the latest revision of the JDK for supported LTS releases: 8, 11, 17 and 21 currently. See https://github.com/apache/commons-lang/blob/master/.github/workflows/maven.yml Please ensure your build environment is up-to-date and kindly report any build issues.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.lang3.mutable;

import java.io.Serializable;
import java.util.Objects;

/**
 * A mutable {@link Object} wrapper.
 *
 * @param  the type to set and get
 * @since 2.1
 */
public class MutableObject implements Mutable, Serializable {

    /**
     * Required for serialization support.
     *
     * @see java.io.Serializable
     */
    private static final long serialVersionUID = 86241875189L;

    /** The mutable value. */
    private T value;

    /**
     * Constructs a new MutableObject with the default value of {@code null}.
     */
    public MutableObject() {
    }

    /**
     * Constructs a new MutableObject with the specified value.
     *
     * @param value  the initial value to store
     */
    public MutableObject(final T value) {
        this.value = value;
    }

    /**
     * Compares this object against the specified object. The result is {@code true} if and only if the argument
     * is not {@code null} and is a {@link MutableObject} object that contains the same {@link T}
     * value as this object.
     *
     * @param obj  the object to compare with, {@code null} returns {@code false}
     * @return  {@code true} if the objects are the same;
     *          {@code true} if the objects have equivalent {@code value} fields;
     *          {@code false} otherwise.
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj == null) {
            return false;
        }
        if (this == obj) {
            return true;
        }
        if (this.getClass() == obj.getClass()) {
            final MutableObject that = (MutableObject) obj;
            return Objects.equals(this.value, that.value);
        }
        return false;
    }

    /**
     * Gets the value.
     *
     * @return the value, may be null
     */
    @Override
    public T getValue() {
        return this.value;
    }

    /**
     * Returns the value's hash code or {@code 0} if the value is {@code null}.
     *
     * @return the value's hash code or {@code 0} if the value is {@code null}.
     */
    @Override
    public int hashCode() {
        return Objects.hashCode(value);
    }

    /**
     * Sets the value.
     *
     * @param value  the value to set
     */
    @Override
    public void setValue(final T value) {
        this.value = value;
    }

    /**
     * Returns the String value of this mutable.
     *
     * @return the mutable value as a string
     */
    @Override
    public String toString() {
        return Objects.toString(value);
    }

}