Package org.apache.commons.collections4.iterators

Class FilterIterator<E>

  • All Implemented Interfaces:
    Iterator<E>
    Direct Known Subclasses:
    UniqueFilterIterator
    public class FilterIterator<E>
extends Object
implements Iterator<E>
    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:
    1.0

    • Constructor Detail

      • 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

    • 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<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.

      • getIterator

        public Iterator<? extends E> getIterator()
        Gets the iterator this iterator is using.
        Returns:
        the iterator

      • 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

      • getPredicate

        public Predicate<? super E> getPredicate()
        Gets the predicate this iterator is using.
        Returns:
        the predicate

      • setPredicate

        public void setPredicate​(Predicate<? super E> predicate)
        Sets the predicate this the iterator to use.
        Parameters:
        predicate - the predicate to use