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.Predicate;
22 import org.apache.commons.collections.SortedBag;
23
24 /**
25 * Decorates another {@link SortedBag} to validate that additions
26 * match a specified predicate.
27 * <p>
28 * This bag exists to provide validation for the decorated bag.
29 * It is normally created to decorate an empty bag.
30 * If an object cannot be added to the bag, an {@link IllegalArgumentException} is thrown.
31 * <p>
32 * One usage would be to ensure that no null entries are added to the bag.
33 * <pre>SortedBag bag = PredicatedSortedBag.decorate(new TreeBag(), NotNullPredicate.INSTANCE);</pre>
34 * <p>
35 * This class is Serializable from Commons Collections 3.1.
36 *
37 * @since 3.0
38 * @version $Id: PredicatedSortedBag.java 1435824 2013-01-20 11:41:17Z tn $
39 */
40 public class PredicatedSortedBag<E> extends PredicatedBag<E> implements SortedBag<E> {
41
42 /** Serialization version */
43 private static final long serialVersionUID = 3448581314086406616L;
44
45 /**
46 * Factory method to create a predicated (validating) bag.
47 * <p>
48 * If there are any elements already in the bag being decorated, they
49 * are validated.
50 *
51 * @param <E> the type of the elements in the bag
52 * @param bag the bag to decorate, must not be null
53 * @param predicate the predicate to use for validation, must not be null
54 * @return a new predicated SortedBag
55 * @throws IllegalArgumentException if bag or predicate is null
56 * @throws IllegalArgumentException if the bag contains invalid elements
57 */
58 public static <E> PredicatedSortedBag<E> predicatedSortedBag(final SortedBag<E> bag,
59 final Predicate<? super E> predicate) {
60 return new PredicatedSortedBag<E>(bag, predicate);
61 }
62
63 //-----------------------------------------------------------------------
64 /**
65 * Constructor that wraps (not copies).
66 * <p>If there are any elements already in the bag being decorated, they
67 * are validated.
68 *
69 * @param bag the bag to decorate, must not be null
70 * @param predicate the predicate to use for validation, must not be null
71 * @throws IllegalArgumentException if bag or predicate is null
72 * @throws IllegalArgumentException if the bag contains invalid elements
73 */
74 protected PredicatedSortedBag(final SortedBag<E> bag, final Predicate<? super E> predicate) {
75 super(bag, predicate);
76 }
77
78 /**
79 * Gets the decorated sorted bag.
80 *
81 * @return the decorated bag
82 */
83 @Override
84 protected SortedBag<E> decorated() {
85 return (SortedBag<E>) super.decorated();
86 }
87
88 //-----------------------------------------------------------------------
89
90 public E first() {
91 return decorated().first();
92 }
93
94 public E last() {
95 return decorated().last();
96 }
97
98 public Comparator<? super E> comparator() {
99 return decorated().comparator();
100 }
101
102 }