001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.logging.log4j.core.util; 018 019import java.util.Iterator; 020import java.util.NoSuchElementException; 021 022/** 023 * An {@link java.util.Iterator Iterator} over an array of objects. 024 * <p> 025 * This iterator does not support {@link #remove}, as the object array cannot be 026 * structurally modified. 027 * <p> 028 * The iterator implements a {@link #reset} method, allowing the reset of the iterator 029 * back to the start if required. 030 * 031 * @param <E> the type to iterate over 032 * @since 3.0 033 * @version $Id: ObjectArrayIterator.java 1734648 2016-03-11 23:51:22Z ggregory $ 034 */ 035public class ObjectArrayIterator<E> implements /*Resettable*/ Iterator<E> { 036 037 /** The array */ 038 final E[] array; 039 /** The start index to loop from */ 040 final int startIndex; 041 /** The end index to loop to */ 042 final int endIndex; 043 /** The current iterator index */ 044 int index = 0; 045 046 //------------------------------------------------------------------------- 047 /** 048 * Constructs an ObjectArrayIterator that will iterate over the values in the 049 * specified array. 050 * 051 * @param array the array to iterate over 052 * @throws NullPointerException if <code>array</code> is <code>null</code> 053 */ 054 @SafeVarargs 055 public ObjectArrayIterator(final E... array) { 056 this(array, 0, array.length); 057 } 058 059 /** 060 * Constructs an ObjectArrayIterator that will iterate over the values in the 061 * specified array from a specific start index. 062 * 063 * @param array the array to iterate over 064 * @param start the index to start iterating at 065 * @throws NullPointerException if <code>array</code> is <code>null</code> 066 * @throws IndexOutOfBoundsException if the start index is out of bounds 067 */ 068 public ObjectArrayIterator(final E array[], final int start) { 069 this(array, start, array.length); 070 } 071 072 /** 073 * Construct an ObjectArrayIterator that will iterate over a range of values 074 * in the specified array. 075 * 076 * @param array the array to iterate over 077 * @param start the index to start iterating at 078 * @param end the index (exclusive) to finish iterating at 079 * @throws IndexOutOfBoundsException if the start or end index is out of bounds 080 * @throws IllegalArgumentException if end index is before the start 081 * @throws NullPointerException if <code>array</code> is <code>null</code> 082 */ 083 public ObjectArrayIterator(final E array[], final int start, final int end) { 084 super(); 085 if (start < 0) { 086 throw new ArrayIndexOutOfBoundsException("Start index must not be less than zero"); 087 } 088 if (end > array.length) { 089 throw new ArrayIndexOutOfBoundsException("End index must not be greater than the array length"); 090 } 091 if (start > array.length) { 092 throw new ArrayIndexOutOfBoundsException("Start index must not be greater than the array length"); 093 } 094 if (end < start) { 095 throw new IllegalArgumentException("End index must not be less than start index"); 096 } 097 this.array = array; 098 this.startIndex = start; 099 this.endIndex = end; 100 this.index = start; 101 } 102 103 // Iterator interface 104 //------------------------------------------------------------------------- 105 106 /** 107 * Returns true if there are more elements to return from the array. 108 * 109 * @return true if there is a next element to return 110 */ 111 @Override 112 public boolean hasNext() { 113 return this.index < this.endIndex; 114 } 115 116 /** 117 * Returns the next element in the array. 118 * 119 * @return the next element in the array 120 * @throws NoSuchElementException if all the elements in the array 121 * have already been returned 122 */ 123 @Override 124 public E next() { 125 if (hasNext() == false) { 126 throw new NoSuchElementException(); 127 } 128 return this.array[this.index++]; 129 } 130 131 /** 132 * Throws {@link UnsupportedOperationException}. 133 * 134 * @throws UnsupportedOperationException always 135 */ 136 @Override 137 public void remove() { 138 throw new UnsupportedOperationException("remove() method is not supported for an ObjectArrayIterator"); 139 } 140 141 // Properties 142 //------------------------------------------------------------------------- 143 144 /** 145 * Gets the array that this iterator is iterating over. 146 * 147 * @return the array this iterator iterates over 148 */ 149 public E[] getArray() { 150 return this.array; 151 } 152 153 /** 154 * Gets the start index to loop from. 155 * 156 * @return the start index 157 */ 158 public int getStartIndex() { 159 return this.startIndex; 160 } 161 162 /** 163 * Gets the end index to loop to. 164 * 165 * @return the end index 166 */ 167 public int getEndIndex() { 168 return this.endIndex; 169 } 170 171 /** 172 * Resets the iterator back to the start index. 173 */ 174 //@Override 175 public void reset() { 176 this.index = this.startIndex; 177 } 178 179}