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.ListIterator; 20 21 import org.apache.commons.collections4.ResettableListIterator; 22 23 /** 24 * Provides an implementation of an empty list iterator. 25 * <p> 26 * This class provides an implementation of an empty list iterator. This class 27 * provides for binary compatibility between Commons Collections 2.1.1 and 3.1 28 * due to issues with {@code IteratorUtils}. 29 * 30 * @param <E> the type of elements returned by this iterator. 31 * @since 2.1.1 and 3.1 32 */ 33 public class EmptyListIterator<E> extends AbstractEmptyIterator<E> implements 34 ResettableListIterator<E> { 35 36 /** 37 * Singleton instance of the iterator. 38 * @since 3.1 39 */ 40 @SuppressWarnings("rawtypes") 41 public static final ResettableListIterator RESETTABLE_INSTANCE = new EmptyListIterator<>(); 42 43 /** 44 * Singleton instance of the iterator. 45 * @since 2.1.1 and 3.1 46 */ 47 @SuppressWarnings("rawtypes") 48 public static final ListIterator INSTANCE = RESETTABLE_INSTANCE; 49 50 /** 51 * Gets a typed instance of the iterator. 52 * @param <E> the element type 53 * @return {@link ListIterator}<E> 54 */ 55 public static <E> ListIterator<E> emptyListIterator() { 56 return INSTANCE; 57 } 58 59 /** 60 * Gets a typed instance of the iterator. 61 * @param <E> the element type 62 * @return {@link ResettableListIterator}<E> 63 */ 64 public static <E> ResettableListIterator<E> resettableEmptyListIterator() { 65 return RESETTABLE_INSTANCE; 66 } 67 68 /** 69 * Constructs a new instance. 70 */ 71 protected EmptyListIterator() { 72 } 73 74 }