org.apache.commons.collections.iterators.ObjectArrayIterator Maven / Gradle / Ivy
/*
* 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 org.apache.commons.collections.iterators;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.commons.collections.ResettableIterator;
/**
* An {@link 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.
*
* @since Commons Collections 3.0
* @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
*
* @author James Strachan
* @author Mauricio S. Moura
* @author Michael A. Smith
* @author Neil O'Toole
* @author Stephen Colebourne
* @author Phil Steitz
*/
public class ObjectArrayIterator
implements Iterator, ResettableIterator {
/** The array */
protected Object[] array = null;
/** The start index to loop from */
protected int startIndex = 0;
/** The end index to loop to */
protected int endIndex = 0;
/** The current iterator index */
protected int index = 0;
/**
* Constructor for use with setArray.
*
* Using this constructor, the iterator is equivalent to an empty iterator
* until {@link #setArray} is called to establish the array to iterate over.
*/
public ObjectArrayIterator() {
super();
}
/**
* 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
*/
public ObjectArrayIterator(Object[] 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(Object array[], 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(Object array[], int start, 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
*/
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
*/
public Object next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
return this.array[this.index++];
}
/**
* Throws {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException always
*/
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, or null if
* the no-arg constructor was used and {@link #setArray} has never
* been called with a valid array.
*/
public Object[] getArray() {
return this.array;
}
/**
* Sets the array that the ArrayIterator should iterate over.
*
* This method may only be called once, otherwise an IllegalStateException
* will occur.
*
* The {@link #reset} method can be used to reset the iterator if required.
*
* @param array the array that the iterator should iterate over
* @throws IllegalStateException if the array was set in the constructor
* @throws NullPointerException if array is null
*/
public void setArray(Object[] array) {
if (this.array != null) {
throw new IllegalStateException("The array to iterate over has already been set");
}
this.array = array;
this.startIndex = 0;
this.endIndex = array.length;
this.index = 0;
}
/**
* 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.
*/
public void reset() {
this.index = this.startIndex;
}
}