    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 */
    017package org.apache.commons.collections4.bag;
    018
    019import java.util.Set;
    020
    021import org.apache.commons.collections4.Bag;
    022import org.apache.commons.collections4.collection.SynchronizedCollection;
    023
    024/**
    025 * Decorates another {@link Bag} to synchronize its behavior
    026 * for a multithreaded environment.
    027 * <p>
    028 * Methods are synchronized, then forwarded to the decorated bag.
    029 * Iterators must be separately synchronized around the loop.
    030 * </p>
    031 * <p>
    032 * This class is Serializable from Commons Collections 3.1.
    033 * </p>
    034 *
    035 * @param <E> the type of elements in this bag
    036 * @since 3.0
    037 */
    038public class SynchronizedBag<E> extends SynchronizedCollection<E> implements Bag<E> {
    039
    040    /**
    041     * Synchronized Set for the Bag class.
    042     */
    043    final class SynchronizedBagSet extends SynchronizedCollection<E> implements Set<E> {
    044        /** Serialization version */
    045        private static final long serialVersionUID = 2990565892366827855L;
    046
    047        /**
    048         * Constructs a new instance.
    049         * @param set  the set to decorate
    050         * @param lock  the lock to use, shared with the bag
    051         */
    052        SynchronizedBagSet(final Set<E> set, final Object lock) {
    053            super(set, lock);
    054        }
    055    }
    056
    057    /** Serialization version */
    058    private static final long serialVersionUID = 8084674570753837109L;
    059
    060    /**
    061     * Factory method to create a synchronized bag.
    062     *
    063     * @param <E> the type of the elements in the bag
    064     * @param bag  the bag to decorate, must not be null
    065     * @return a new synchronized Bag
    066     * @throws NullPointerException if bag is null
    067     * @since 4.0
    068     */
    069    public static <E> SynchronizedBag<E> synchronizedBag(final Bag<E> bag) {
    070        return new SynchronizedBag<>(bag);
    071    }
    072
    073    /**
    074     * Constructor that wraps (not copies).
    075     *
    076     * @param bag  the bag to decorate, must not be null
    077     * @throws NullPointerException if bag is null
    078     */
    079    protected SynchronizedBag(final Bag<E> bag) {
    080        super(bag);
    081    }
    082
    083    /**
    084     * Constructor that wraps (not copies).
    085     *
    086     * @param bag  the bag to decorate, must not be null
    087     * @param lock  the lock to use, must not be null
    088     * @throws NullPointerException if bag or lock is null
    089     */
    090    protected SynchronizedBag(final Bag<E> bag, final Object lock) {
    091        super(bag, lock);
    092    }
    093
    094    @Override
    095    public boolean add(final E object, final int count) {
    096        synchronized (lock) {
    097            return getBag().add(object, count);
    098        }
    099    }
    100
    101    @Override
    102    public boolean equals(final Object object) {
    103        if (object == this) {
    104            return true;
    105        }
    106        synchronized (lock) {
    107            return getBag().equals(object);
    108        }
    109    }
    110
    111    /**
    112     * Gets the bag being decorated.
    113     *
    114     * @return the decorated bag
    115     */
    116    protected Bag<E> getBag() {
    117        return (Bag<E>) decorated();
    118    }
    119
    120    @Override
    121    public int getCount(final Object object) {
    122        synchronized (lock) {
    123            return getBag().getCount(object);
    124        }
    125    }
    126
    127    @Override
    128    public int hashCode() {
    129        synchronized (lock) {
    130            return getBag().hashCode();
    131        }
    132    }
    133
    134    @Override
    135    public boolean remove(final Object object, final int count) {
    136        synchronized (lock) {
    137            return getBag().remove(object, count);
    138        }
    139    }
    140
    141    @Override
    142    public Set<E> uniqueSet() {
    143        synchronized (lock) {
    144            final Set<E> set = getBag().uniqueSet();
    145            return new SynchronizedBagSet(set, lock);
    146        }
    147    }
    148
    149}