    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.Comparator;
    020
    021import org.apache.commons.collections4.Bag;
    022import org.apache.commons.collections4.SortedBag;
    023
    024/**
    025 * Decorates another {@link SortedBag} 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 SynchronizedSortedBag<E> extends SynchronizedBag<E> implements SortedBag<E> {
    039
    040    /** Serialization version */
    041    private static final long serialVersionUID = 722374056718497858L;
    042
    043    /**
    044     * Factory method to create a synchronized sorted 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 SortedBag
    049     * @throws NullPointerException if bag is null
    050     * @since 4.0
    051     */
    052    public static <E> SynchronizedSortedBag<E> synchronizedSortedBag(final SortedBag<E> bag) {
    053        return new SynchronizedSortedBag<>(bag);
    054    }
    055
    056    /**
    057     * Constructor that wraps (not copies).
    058     *
    059     * @param bag  the bag to decorate, must not be null
    060     * @param lock  the lock to use, must not be null
    061     * @throws NullPointerException if bag or lock is null
    062     */
    063    protected SynchronizedSortedBag(final Bag<E> bag, final Object lock) {
    064        super(bag, lock);
    065    }
    066
    067    /**
    068     * Constructor that wraps (not copies).
    069     *
    070     * @param bag  the bag to decorate, must not be null
    071     * @throws NullPointerException if bag is null
    072     */
    073    protected SynchronizedSortedBag(final SortedBag<E> bag) {
    074        super(bag);
    075    }
    076
    077    @Override
    078    public synchronized Comparator<? super E> comparator() {
    079        synchronized (lock) {
    080            return getSortedBag().comparator();
    081        }
    082    }
    083
    084    @Override
    085    public synchronized E first() {
    086        synchronized (lock) {
    087            return getSortedBag().first();
    088        }
    089    }
    090
    091    /**
    092     * Gets the bag being decorated.
    093     *
    094     * @return the decorated bag
    095     */
    096    protected SortedBag<E> getSortedBag() {
    097        return (SortedBag<E>) decorated();
    098    }
    099
    100    @Override
    101    public synchronized E last() {
    102        synchronized (lock) {
    103            return getSortedBag().last();
    104        }
    105    }
    106
    107}