Class FilterIterator<E>

java.lang.Object

org.apache.commons.collections4.iterators.FilterIterator<E>

Type Parameters:

E - the type of elements returned by this iterator.

All Implemented Interfaces:

Iterator<E>, IteratorOperations<E>

Direct Known Subclasses:

UniqueFilterIterator

public class FilterIterator<E>
extends Object
implements IteratorOperations<E>

Decorates an Iterator using an optional predicate to filter elements.

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

Since:

1.0

Constructor Summary

Constructors

Constructor	Description
FilterIterator()	Constructs a new FilterIterator that will not function until setIterator is invoked.
FilterIterator(Iterator<? extends E> iterator)	Constructs a new FilterIterator that will not function until setPredicate is invoked.
FilterIterator(Iterator<? extends E> iterator, Predicate<? super E> predicate)	Constructs a new FilterIterator that will use the given iterator and predicate.

Method Summary

Modifier and Type	Method	Description
Iterator<? extends E>	getIterator()	Gets the iterator this iterator is using.
Predicate<? super E>	getPredicate()	Gets the predicate this iterator is using.
boolean	hasNext()	Returns true if the underlying iterator contains an object that matches the predicate.
E	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<? extends E> iterator)	Sets the iterator for this iterator to use.
void	setPredicate(Predicate<? super E> predicate)	Sets the predicate this the iterator to use where null accepts all values.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator

forEachRemaining

Methods inherited from interface org.apache.commons.collections4.iterators.IteratorOperations

addTo, removeNext, toCollection, toList, toSet

Constructor Details

FilterIterator

public FilterIterator()

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

FilterIterator

public FilterIterator(Iterator<? extends E> iterator)

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

Parameters:

iterator - the iterator to use

FilterIterator

public FilterIterator(Iterator<? extends E> iterator,
 Predicate<? super E> predicate)

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

Parameters:

iterator - the iterator to use

predicate - the predicate to use, null accepts all values.

Method Details

getIterator

public Iterator<? extends E> getIterator()

Gets the iterator this iterator is using.

Returns:

the underlying iterator.

getPredicate

public Predicate<? super E> getPredicate()

Gets the predicate this iterator is using.

Returns:

the filtering predicate.

hasNext

public boolean hasNext()

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

Specified by:

hasNext in interface Iterator<E>

Returns:

true if there is another object that matches the predicate

Throws:

NullPointerException - if either the iterator or predicate are null

next

public E next()

Returns the next object that matches the predicate.

Specified by:

next in interface Iterator<E>

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

remove

public void remove()

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.

Specified by:

remove in interface Iterator<E>

Throws:

IllegalStateException - if hasNext() has already been called.

setIterator

public void setIterator(Iterator<? extends E> 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<? super E> predicate)

Sets the predicate this the iterator to use where null accepts all values.

Parameters:

predicate - the predicate to use, null accepts all values.