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.iterators;
18
19 import java.util.Objects;
20
21 import org.apache.commons.collections4.OrderedMapIterator;
22 import org.apache.commons.collections4.Unmodifiable;
23
24 /**
25 * Decorates an ordered map iterator such that it cannot be modified.
26 * <p>
27 * Attempts to modify it will result in an UnsupportedOperationException.
28 * </p>
29 *
30 * @param <K> the type of keys
31 * @param <V> the type of mapped values
32 * @since 3.0
33 */
34 public final class UnmodifiableOrderedMapIterator<K, V> implements OrderedMapIterator<K, V>,
35 Unmodifiable {
36
37 /**
38 * Decorates the specified iterator such that it cannot be modified.
39 *
40 * @param <K> the key type
41 * @param <V> the value type
42 * @param iterator the iterator to decorate
43 * @return a new unmodifiable ordered map iterator
44 * @throws NullPointerException if the iterator is null
45 */
46 public static <K, V> OrderedMapIterator<K, V> unmodifiableOrderedMapIterator(
47 final OrderedMapIterator<K, ? extends V> iterator) {
48 Objects.requireNonNull(iterator, "iterator");
49 if (iterator instanceof Unmodifiable) {
50 @SuppressWarnings("unchecked") // safe to upcast
51 final OrderedMapIterator<K, V> tmpIterator = (OrderedMapIterator<K, V>) iterator;
52 return tmpIterator;
53 }
54 return new UnmodifiableOrderedMapIterator<>(iterator);
55 }
56
57 /** The iterator being decorated */
58 private final OrderedMapIterator<? extends K, ? extends V> iterator;
59
60 /**
61 * Constructs a new instance.
62 *
63 * @param iterator the iterator to decorate
64 */
65 private UnmodifiableOrderedMapIterator(final OrderedMapIterator<K, ? extends V> iterator) {
66 this.iterator = iterator;
67 }
68
69 @Override
70 public K getKey() {
71 return iterator.getKey();
72 }
73
74 @Override
75 public V getValue() {
76 return iterator.getValue();
77 }
78
79 @Override
80 public boolean hasNext() {
81 return iterator.hasNext();
82 }
83
84 @Override
85 public boolean hasPrevious() {
86 return iterator.hasPrevious();
87 }
88
89 @Override
90 public K next() {
91 return iterator.next();
92 }
93
94 @Override
95 public K previous() {
96 return iterator.previous();
97 }
98
99 @Override
100 public void remove() {
101 throw new UnsupportedOperationException("remove() is not supported");
102 }
103
104 @Override
105 public V setValue(final V value) {
106 throw new UnsupportedOperationException("setValue() is not supported");
107 }
108
109 }