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 *      https://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.util.function.Supplier;
021
022/**
023 * Provides mutable access to a value.
024 * <p>
025 * {@link Mutable} is used as a generic interface to the implementations in this package.
026 * </p>
027 * <p>
028 * A typical use case would be to enable a primitive or string to be passed to a method and allow that method to effectively change the value of the
029 * primitive/object. Another use case is to store a frequently changing primitive in a collection (for example a total in a map) without needing to create new
030 * Integer/Long wrapper objects.
031 * </p>
032 *
033 * @param <T> the type to wrap.
034 * @since 2.1
035 */
036public interface Mutable<T> extends Supplier<T> {
037
038    /**
039     * Gets the value of this mutable.
040     *
041     * @return the stored value.
042     * @since 3.18.0
043     */
044    @Override
045    default T get() {
046        return getValue();
047    }
048
049    /**
050     * Gets the value of this mutable.
051     *
052     * @return the stored value
053     * @deprecated Use {@link #get()}.
054     */
055    @Deprecated
056    T getValue();
057
058    /**
059     * Sets the value of this mutable.
060     *
061     * @param value the value to store
062     * @throws NullPointerException if the object is null and null is invalid.
063     * @throws ClassCastException   if the type is invalid.
064     */
065    void setValue(T value);
066}