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## org.apache.commons.collections.iterators
Class FilterIterator

    java.lang.Object
      |
      +--org.apache.commons.collections.iterators.FilterIterator

All Implemented Interfaces:
  Iterator

Direct Known Subclasses:
  UniqueFilterIterator

public class FilterIterator
extends Object
implements Iterator

Decorates an iterator such that only elements matching a predicate filter are returned.

Since:
  Commons Collections 1.0
Version:
  $Revision: 1.8 $ $Date: 2004/02/18 00:59:50 $
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.

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(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

### hasNext

    public boolean hasNext()

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

  Specified by:
    `hasNext` in interface `Iterator`
  Returns:
    true if there is another object that matches the predicate

### next

    public Object next()

  Returns the next object that matches the predicate.

  Specified by:
    `next` in interface `Iterator`
  Returns:
    the next object which matches the given predicate
  Throws:
    `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`
  Throws:
    `IllegalStateException` - if `hasNext()` has already been called.

### getIterator

    public Iterator getIterator()

  Gets the iterator this iterator is using.

  Returns:
    the iterator.

### 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

### getPredicate

    public Predicate getPredicate()

  Gets the predicate this iterator is using.

  Returns:
    the predicate.

### setPredicate

    public void setPredicate(Predicate predicate)

  Sets the predicate this the iterator to use.

  Parameters:
    `predicate` - the transformer to use

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