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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.feilong.lib.collection4.iterators;
import java.util.NoSuchElementException;
import org.apache.commons.collections4.ResettableIterator;
/**
* An {@link java.util.Iterator Iterator} over an array of objects.
*
* This iterator does not support {@link #remove}, as the object array cannot be
* structurally modified.
*
* The iterator implements a {@link #reset} method, allowing the reset of the iterator
* back to the start if required.
*
* @param
* the type of elements returned by this iterator
* @since 3.0
*/
public class ObjectArrayIterator implements ResettableIterator{
/** The array */
final E[] array;
/** The start index to loop from */
final int startIndex;
/** The end index to loop to */
final int endIndex;
/** The current iterator index */
int index = 0;
//-------------------------------------------------------------------------
/**
* Constructs an ObjectArrayIterator that will iterate over the values in the
* specified array.
*
* @param array
* the array to iterate over
* @throws NullPointerException
* if array is null
*/
@SafeVarargs
public ObjectArrayIterator(final E...array){
this(array, 0, array.length);
}
/**
* Constructs an ObjectArrayIterator that will iterate over the values in the
* specified array from a specific start index.
*
* @param array
* the array to iterate over
* @param start
* the index to start iterating at
* @throws NullPointerException
* if array is null
* @throws IndexOutOfBoundsException
* if the start index is out of bounds
*/
public ObjectArrayIterator(final E array[], final int start){
this(array, start, array.length);
}
/**
* Construct an ObjectArrayIterator that will iterate over a range of values
* in the specified array.
*
* @param array
* the array to iterate over
* @param start
* the index to start iterating at
* @param end
* the index (exclusive) to finish iterating at
* @throws IndexOutOfBoundsException
* if the start or end index is out of bounds
* @throws IllegalArgumentException
* if end index is before the start
* @throws NullPointerException
* if array is null
*/
public ObjectArrayIterator(final E array[], final int start, final int end){
super();
if (start < 0){
throw new ArrayIndexOutOfBoundsException("Start index must not be less than zero");
}
if (end > array.length){
throw new ArrayIndexOutOfBoundsException("End index must not be greater than the array length");
}
if (start > array.length){
throw new ArrayIndexOutOfBoundsException("Start index must not be greater than the array length");
}
if (end < start){
throw new IllegalArgumentException("End index must not be less than start index");
}
this.array = array;
this.startIndex = start;
this.endIndex = end;
this.index = start;
}
// Iterator interface
//-------------------------------------------------------------------------
/**
* Returns true if there are more elements to return from the array.
*
* @return true if there is a next element to return
*/
@Override
public boolean hasNext(){
return this.index < this.endIndex;
}
/**
* Returns the next element in the array.
*
* @return the next element in the array
* @throws NoSuchElementException
* if all the elements in the array
* have already been returned
*/
@Override
public E next(){
if (hasNext() == false){
throw new NoSuchElementException();
}
return this.array[this.index++];
}
/**
* Throws {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException
* always
*/
@Override
public void remove(){
throw new UnsupportedOperationException("remove() method is not supported for an ObjectArrayIterator");
}
// Properties
//-------------------------------------------------------------------------
/**
* Gets the array that this iterator is iterating over.
*
* @return the array this iterator iterates over
*/
public E[] getArray(){
return this.array;
}
/**
* Gets the start index to loop from.
*
* @return the start index
*/
public int getStartIndex(){
return this.startIndex;
}
/**
* Gets the end index to loop to.
*
* @return the end index
*/
public int getEndIndex(){
return this.endIndex;
}
/**
* Resets the iterator back to the start index.
*/
@Override
public void reset(){
this.index = this.startIndex;
}
}