/*
 * 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.collections4.bag;

import java.util.Set;

import org.apache.commons.collections4.Bag;
import org.apache.commons.collections4.collection.SynchronizedCollection;

/**
 * Decorates another {@link Bag} to synchronize its behaviour
 * for a multi-threaded environment.
 * 

* Methods are synchronized, then forwarded to the decorated bag. * Iterators must be separately synchronized around the loop. *

* This class is Serializable from Commons Collections 3.1. * * @since 3.0 * @version $Id$ */ public class SynchronizedBag extends SynchronizedCollection implements Bag { /** Serialization version */ private static final long serialVersionUID = 8084674570753837109L; /** * Factory method to create a synchronized bag. * * @param the type of the elements in the bag * @param bag the bag to decorate, must not be null * @return a new synchronized Bag * @throws NullPointerException if bag is null * @since 4.0 */ public static SynchronizedBag synchronizedBag(final Bag bag) { return new SynchronizedBag(bag); } //----------------------------------------------------------------------- /** * Constructor that wraps (not copies). * * @param bag the bag to decorate, must not be null * @throws NullPointerException if bag is null */ protected SynchronizedBag(final Bag bag) { super(bag); } /** * Constructor that wraps (not copies). * * @param bag the bag to decorate, must not be null * @param lock the lock to use, must not be null * @throws NullPointerException if bag or lock is null */ protected SynchronizedBag(final Bag bag, final Object lock) { super(bag, lock); } /** * Gets the bag being decorated. * * @return the decorated bag */ protected Bag getBag() { return (Bag) decorated(); } @Override public boolean equals(final Object object) { if (object == this) { return true; } synchronized (lock) { return getBag().equals(object); } } @Override public int hashCode() { synchronized (lock) { return getBag().hashCode(); } } //----------------------------------------------------------------------- @Override public boolean add(final E object, final int count) { synchronized (lock) { return getBag().add(object, count); } } @Override public boolean remove(final Object object, final int count) { synchronized (lock) { return getBag().remove(object, count); } } @Override public Set uniqueSet() { synchronized (lock) { final Set set = getBag().uniqueSet(); return new SynchronizedBagSet(set, lock); } } @Override public int getCount(final Object object) { synchronized (lock) { return getBag().getCount(object); } } //----------------------------------------------------------------------- /** * Synchronized Set for the Bag class. */ class SynchronizedBagSet extends SynchronizedCollection implements Set { /** Serialization version */ private static final long serialVersionUID = 2990565892366827855L; /** * Constructor. * @param set the set to decorate * @param lock the lock to use, shared with the bag */ SynchronizedBagSet(final Set set, final Object lock) { super(set, lock); } } }