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.NoSuchElementException;
20
21 /**
22 * Provides an implementation of an empty iterator.
23 *
24 * @since 3.1
25 */
26 abstract class AbstractEmptyIterator<E> {
27
28 /**
29 * Constructs a new instance.
30 */
31 protected AbstractEmptyIterator() {
32 }
33
34 public void add(final E obj) {
35 throw new UnsupportedOperationException("add() not supported for empty Iterator");
36 }
37
38 public boolean hasNext() {
39 return false;
40 }
41
42 public boolean hasPrevious() {
43 return false;
44 }
45
46 public E next() {
47 throw new NoSuchElementException("Iterator contains no elements");
48 }
49
50 public int nextIndex() {
51 return 0;
52 }
53
54 public E previous() {
55 throw new NoSuchElementException("Iterator contains no elements");
56 }
57
58 public int previousIndex() {
59 return -1;
60 }
61
62 public void remove() {
63 throw new IllegalStateException("Iterator contains no elements");
64 }
65
66 public void reset() {
67 // do nothing
68 }
69
70 public void set(final E obj) {
71 throw new IllegalStateException("Iterator contains no elements");
72 }
73
74 }