1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections.bag;
18
19 import java.util.Comparator;
20
21 import org.apache.commons.collections.Bag;
22 import org.apache.commons.collections.SortedBag;
23
24 /**
25 * Decorates another {@link SortedBag} to synchronize its behaviour
26 * for a multi-threaded environment.
27 * <p>
28 * Methods are synchronized, then forwarded to the decorated bag.
29 * Iterators must be separately synchronized around the loop.
30 * <p>
31 * This class is Serializable from Commons Collections 3.1.
32 *
33 * @since 3.0
34 * @version $Id: SynchronizedSortedBag.java 1429905 2013-01-07 17:15:14Z ggregory $
35 */
36 public class SynchronizedSortedBag<E> extends SynchronizedBag<E> implements SortedBag<E> {
37
38 /** Serialization version */
39 private static final long serialVersionUID = 722374056718497858L;
40
41 /**
42 * Factory method to create a synchronized sorted bag.
43 *
44 * @param <E> the type of the elements in the bag
45 * @param bag the bag to decorate, must not be null
46 * @return a new synchronized SortedBag
47 * @throws IllegalArgumentException if bag is null
48 */
49 public static <E> SynchronizedSortedBag<E> synchronizedSortedBag(final SortedBag<E> bag) {
50 return new SynchronizedSortedBag<E>(bag);
51 }
52
53 //-----------------------------------------------------------------------
54 /**
55 * Constructor that wraps (not copies).
56 *
57 * @param bag the bag to decorate, must not be null
58 * @throws IllegalArgumentException if bag is null
59 */
60 protected SynchronizedSortedBag(final SortedBag<E> bag) {
61 super(bag);
62 }
63
64 /**
65 * Constructor that wraps (not copies).
66 *
67 * @param bag the bag to decorate, must not be null
68 * @param lock the lock to use, must not be null
69 * @throws IllegalArgumentException if bag is null
70 */
71 protected SynchronizedSortedBag(final Bag<E> bag, final Object lock) {
72 super(bag, lock);
73 }
74
75 /**
76 * Gets the bag being decorated.
77 *
78 * @return the decorated bag
79 */
80 protected SortedBag<E> getSortedBag() {
81 return (SortedBag<E>) collection;
82 }
83
84 //-----------------------------------------------------------------------
85
86 public synchronized E first() {
87 synchronized (lock) {
88 return getSortedBag().first();
89 }
90 }
91
92 public synchronized E last() {
93 synchronized (lock) {
94 return getSortedBag().last();
95 }
96 }
97
98 public synchronized Comparator<? super E> comparator() {
99 synchronized (lock) {
100 return getSortedBag().comparator();
101 }
102 }
103
104 }