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.collections4.bag;
18
19 import java.util.Comparator;
20
21 import org.apache.commons.collections4.SortedBag;
22 import org.apache.commons.collections4.Transformer;
23
24 /**
25 * Decorates another {@link SortedBag} to transform objects that are added.
26 * <p>
27 * The add methods are affected by this class.
28 * Thus objects must be removed or searched for using their transformed form.
29 * For example, if the transformation converts Strings to Integers, you must
30 * use the Integer form to remove objects.
31 * </p>
32 * <p>
33 * This class is Serializable from Commons Collections 3.1.
34 * </p>
35 *
36 * @param <E> the type of elements in this bag
37 * @since 3.0
38 */
39 public class TransformedSortedBag<E> extends TransformedBag<E> implements SortedBag<E> {
40
41 /** Serialization version */
42 private static final long serialVersionUID = -251737742649401930L;
43
44 /**
45 * Factory method to create a transforming sorted bag.
46 * <p>
47 * If there are any elements already in the bag being decorated, they
48 * are NOT transformed. Contrast this with {@link #transformedSortedBag(SortedBag, Transformer)}.
49 *
50 * @param <E> the type of the elements in the bag
51 * @param bag the bag to decorate, must not be null
52 * @param transformer the transformer to use for conversion, must not be null
53 * @return a new transformed SortedBag
54 * @throws NullPointerException if bag or transformer is null
55 * @since 4.0
56 */
57 public static <E> TransformedSortedBag<E> transformingSortedBag(final SortedBag<E> bag,
58 final Transformer<? super E, ? extends E> transformer) {
59 return new TransformedSortedBag<>(bag, transformer);
60 }
61
62 /**
63 * Factory method to create a transforming sorted bag that will transform
64 * existing contents of the specified sorted bag.
65 * <p>
66 * If there are any elements already in the bag being decorated, they
67 * will be transformed by this method.
68 * Contrast this with {@link #transformingSortedBag(SortedBag, Transformer)}.
69 *
70 * @param <E> the type of the elements in the bag
71 * @param bag the bag to decorate, must not be null
72 * @param transformer the transformer to use for conversion, must not be null
73 * @return a new transformed SortedBag
74 * @throws NullPointerException if bag or transformer is null
75 * @since 4.0
76 */
77 public static <E> TransformedSortedBag<E> transformedSortedBag(final SortedBag<E> bag,
78 final Transformer<? super E, ? extends E> transformer) {
79
80 final TransformedSortedBag<E> decorated = new TransformedSortedBag<>(bag, transformer);
81 if (bag.size() > 0) {
82 @SuppressWarnings("unchecked") // bag is type E
83 final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
84 bag.clear();
85 for (final E value : values) {
86 decorated.decorated().add(transformer.transform(value));
87 }
88 }
89 return decorated;
90 }
91
92 //-----------------------------------------------------------------------
93 /**
94 * Constructor that wraps (not copies).
95 * <p>
96 * If there are any elements already in the bag being decorated, they
97 * are NOT transformed.
98 *
99 * @param bag the bag to decorate, must not be null
100 * @param transformer the transformer to use for conversion, must not be null
101 * @throws NullPointerException if bag or transformer is null
102 */
103 protected TransformedSortedBag(final SortedBag<E> bag, final Transformer<? super E, ? extends E> transformer) {
104 super(bag, transformer);
105 }
106
107 /**
108 * Gets the decorated bag.
109 *
110 * @return the decorated bag
111 */
112 protected SortedBag<E> getSortedBag() {
113 return (SortedBag<E>) decorated();
114 }
115
116 //-----------------------------------------------------------------------
117
118 @Override
119 public E first() {
120 return getSortedBag().first();
121 }
122
123 @Override
124 public E last() {
125 return getSortedBag().last();
126 }
127
128 @Override
129 public Comparator<? super E> comparator() {
130 return getSortedBag().comparator();
131 }
132
133 }