org.apache.commons.collections.iterators

Class FilterIterator

java.lang.Object

org.apache.commons.collections.iterators.ProxyIterator

org.apache.commons.collections.iterators.FilterIterator

All Implemented Interfaces:

java.util.Iterator

Direct Known Subclasses:

UniqueFilterIterator

public class FilterIterator
extends ProxyIterator

A Proxy Iterator which takes a Predicate instance to filter out objects from an underlying Iterator instance. Only objects for which the specified Predicate evaluates to true are returned.

Since:

1.0

Author:

James Strachan, Jan Sorensen

Constructor Summary

Constructors

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

Method Summary

Methods

Modifier and Type	Method and Description
Predicate	getPredicate() Getter for property predicate.
boolean	hasNext() Returns true if the underlying iterator contains an object that matches the predicate.
java.lang.Object	next() Returns the next object that matches the predicate.
void	remove() Always throws UnsupportedOperationException as this class does look-ahead with its internal iterator.
void	setPredicate(Predicate predicate) Setter for property predicate.

Methods inherited from class org.apache.commons.collections.iterators.ProxyIterator

getIterator, setIterator

Methods inherited from class java.lang.Object

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

Constructor Detail

FilterIterator

public FilterIterator()

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

FilterIterator

public FilterIterator(java.util.Iterator iterator)

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

Parameters:

iterator - the iterator to use

FilterIterator

public FilterIterator(java.util.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

getPredicate

public Predicate getPredicate()

Getter for property predicate.

Returns:

Value of property predicate.

hasNext

public boolean hasNext()

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

Specified by:

hasNext in interface java.util.Iterator

Overrides:

hasNext in class ProxyIterator

Returns:

true if there is another object that matches the predicate

next

public java.lang.Object next()

Returns the next object that matches the predicate.

Specified by:

next in interface java.util.Iterator

Overrides:

next in class ProxyIterator

Returns:

the next object which matches the given predicate

Throws:

java.util.NoSuchElementException - if there are no more elements that match the predicate

remove

public void remove()

Always throws UnsupportedOperationException as this class does look-ahead with its internal iterator.

Specified by:

remove in interface java.util.Iterator

Overrides:

remove in class ProxyIterator

Throws:

java.lang.UnsupportedOperationException - always

setPredicate

public void setPredicate(Predicate predicate)

Setter for property predicate.

Parameters:

predicate - New value of property predicate.