org.apache.commons.collections.iterators

Class LoopingIterator

public class LoopingIterator extends Object implements ResettableIterator

An Iterator that restarts when it reaches the end.

The iterator will loop continuously around the provided elements, unless there are no elements in the collection to begin with, or all the elements have been removed.

Concurrent modifications are not directly supported, and for most collection implementations will throw a ConcurrentModificationException.

Since: Commons Collections 3.0

Version: $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $

Author: Jonathan Carlson Stephen Colebourne

Constructor Summary
LoopingIterator(Collection coll)
Constructor that wraps a collection.
Method Summary
booleanhasNext()
Has the iterator any more elements.
Objectnext()
Returns the next object in the collection.
voidremove()
Removes the previously retrieved item from the underlying collection.
voidreset()
Resets the iterator back to the start of the collection.
intsize()
Gets the size of the collection underlying the iterator.

Constructor Detail

LoopingIterator

public LoopingIterator(Collection coll)
Constructor that wraps a collection.

There is no way to reset an Iterator instance without recreating it from the original source, so the Collection must be passed in.

Parameters: coll the collection to wrap

Throws: NullPointerException if the collection is null

Method Detail

hasNext

public boolean hasNext()
Has the iterator any more elements.

Returns false only if the collection originally had zero elements, or all the elements have been removed.

Returns: true if there are more elements

next

public Object next()
Returns the next object in the collection.

If at the end of the collection, return the first element.

Throws: NoSuchElementException if there are no elements at all. Use LoopingIterator to avoid this error.

remove

public void remove()
Removes the previously retrieved item from the underlying collection.

This feature is only supported if the underlying collection's Collection#iterator iterator method returns an implementation that supports it.

This method can only be called after at least one LoopingIterator method call. After a removal, the remove method may not be called again until another next has been performed. If the LoopingIterator is called, then remove may not be called until LoopingIterator is called again.

reset

public void reset()
Resets the iterator back to the start of the collection.

size

public int size()
Gets the size of the collection underlying the iterator.

Returns: the current collection size

Copyright © 2001-2008 Apache Software Foundation. All Rights Reserved.