    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 behaviour
    026 * for a multi-threaded 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    /** Serialization version */
    041    private static final long serialVersionUID = 8084674570753837109L;
    042
    043    /**
    044     * Factory method to create a synchronized bag.
    045     *
    046     * @param <E> the type of the elements in the bag
    047     * @param bag  the bag to decorate, must not be null
    048     * @return a new synchronized Bag
    049     * @throws NullPointerException if bag is null
    050     * @since 4.0
    051     */
    052    public static <E> SynchronizedBag<E> synchronizedBag(final Bag<E> bag) {
    053        return new SynchronizedBag<>(bag);
    054    }
    055
    056    //-----------------------------------------------------------------------
    057    /**
    058     * Constructor that wraps (not copies).
    059     *
    060     * @param bag  the bag to decorate, must not be null
    061     * @throws NullPointerException if bag is null
    062     */
    063    protected SynchronizedBag(final Bag<E> bag) {
    064        super(bag);
    065    }
    066
    067    /**
    068     * Constructor that wraps (not copies).
    069     *
    070     * @param bag  the bag to decorate, must not be null
    071     * @param lock  the lock to use, must not be null
    072     * @throws NullPointerException if bag or lock is null
    073     */
    074    protected SynchronizedBag(final Bag<E> bag, final Object lock) {
    075        super(bag, lock);
    076    }
    077
    078    /**
    079     * Gets the bag being decorated.
    080     *
    081     * @return the decorated bag
    082     */
    083    protected Bag<E> getBag() {
    084        return (Bag<E>) decorated();
    085    }
    086
    087    @Override
    088    public boolean equals(final Object object) {
    089        if (object == this) {
    090            return true;
    091        }
    092        synchronized (lock) {
    093            return getBag().equals(object);
    094        }
    095    }
    096
    097    @Override
    098    public int hashCode() {
    099        synchronized (lock) {
    100            return getBag().hashCode();
    101        }
    102    }
    103
    104    //-----------------------------------------------------------------------
    105
    106    @Override
    107    public boolean add(final E object, final int count) {
    108        synchronized (lock) {
    109            return getBag().add(object, count);
    110        }
    111    }
    112
    113    @Override
    114    public boolean remove(final Object object, final int count) {
    115        synchronized (lock) {
    116            return getBag().remove(object, count);
    117        }
    118    }
    119
    120    @Override
    121    public Set<E> uniqueSet() {
    122        synchronized (lock) {
    123            final Set<E> set = getBag().uniqueSet();
    124            return new SynchronizedBagSet(set, lock);
    125        }
    126    }
    127
    128    @Override
    129    public int getCount(final Object object) {
    130        synchronized (lock) {
    131            return getBag().getCount(object);
    132        }
    133    }
    134
    135    //-----------------------------------------------------------------------
    136    /**
    137     * Synchronized Set for the Bag class.
    138     */
    139    class SynchronizedBagSet extends SynchronizedCollection<E> implements Set<E> {
    140        /** Serialization version */
    141        private static final long serialVersionUID = 2990565892366827855L;
    142
    143        /**
    144         * Constructor.
    145         * @param set  the set to decorate
    146         * @param lock  the lock to use, shared with the bag
    147         */
    148        SynchronizedBagSet(final Set<E> set, final Object lock) {
    149            super(set, lock);
    150        }
    151    }
    152
    153}