org.apache.commons.collections.iterators

Class FilterIterator

public class FilterIterator extends Object implements Iterator

Decorates another Iterator using a predicate to filter elements.

This iterator decorates the underlying iterator, only allowing through those elements that match the specified Predicate.

Since: Commons Collections 1.0

Version: $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author: James Strachan Jan Sorensen Ralph Wagner Stephen Colebourne

Constructor Summary
	FilterIterator() Constructs a new `FilterIterator` that will not function until `setIterator` is invoked.
	FilterIterator(Iterator iterator) Constructs a new `FilterIterator` that will not function until `setPredicate` is invoked.
	FilterIterator(Iterator iterator, Predicate predicate) Constructs a new `FilterIterator` that will use the given iterator and predicate.

Method Summary
Iterator	getIterator() Gets the iterator this iterator is using.
Predicate	getPredicate() Gets the predicate this iterator is using.
boolean	hasNext() Returns true if the underlying iterator contains an object that matches the predicate.
Object	next() Returns the next object that matches the predicate.
void	remove() Removes from the underlying collection of the base iterator the last element returned by this iterator.
void	setIterator(Iterator iterator) Sets the iterator for this iterator to use.
void	setPredicate(Predicate predicate) Sets the predicate this the iterator to use.

Constructor Detail

FilterIterator

public FilterIterator()

Constructs a new FilterIterator that will not function until setIterator is invoked.

FilterIterator

public FilterIterator(Iterator iterator)

Constructs a new FilterIterator that will not function until setPredicate is invoked.

Parameters: iterator the iterator to use

FilterIterator

public FilterIterator(Iterator iterator, Predicate predicate)

Constructs a new FilterIterator that will use the given iterator and predicate.

Parameters: iterator the iterator to use predicate the predicate to use

Method Detail

getIterator

public Iterator getIterator()

Gets the iterator this iterator is using.

Returns: the iterator

getPredicate

public Predicate getPredicate()

Gets the predicate this iterator is using.

Returns: the predicate

hasNext

public boolean hasNext()

Returns true if the underlying iterator contains an object that matches the predicate.

Returns: true if there is another object that matches the predicate

Throws: NullPointerException if either the iterator or predicate are null

public Object next()

Returns the next object that matches the predicate.

Returns: the next object which matches the given predicate

Throws: NullPointerException if either the iterator or predicate are null NoSuchElementException if there are no more elements that match the predicate

Removes from the underlying collection of the base iterator the last element returned by this iterator. This method can only be called if next() was called, but not after hasNext(), because the hasNext() call changes the base iterator.

Throws: IllegalStateException if hasNext() has already been called.

setIterator

public void setIterator(Iterator iterator)

Sets the iterator for this iterator to use. If iteration has started, this effectively resets the iterator.

Parameters: iterator the iterator to use

setPredicate

public void setPredicate(Predicate predicate)

Sets the predicate this the iterator to use.

Parameters: predicate the predicate to use