java.util

Interface Iterator<E>

Type Parameters:

E - the type of elements returned by this iterator

All Known Subinterfaces:

ListIterator<E>

public interface Iterator<E>

An iterator over a collection. Iterator takes the place of Enumeration in the Java Collections Framework. Iterators differ from enumerations in two ways:

• Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics.
• Method names have been improved.

This interface is a member of the Java Collections Framework.

Since:

1.2

Author:

Josh Bloch

See Also:

Collection, ListIterator, Iterable

Method Summary

Methods

Modifier and Type	Method and Description
boolean	hasNext() Returns true if the iteration has more elements.
E	next() Returns the next element in the iteration.
void	remove() Removes from the underlying collection the last element returned by this iterator (optional operation).

Method Detail

hasNext

boolean hasNext()

Returns true if the iteration has more elements. (In other words, returns true if next() would return an element rather than throwing an exception.)

Returns:

true if the iteration has more elements

next

E next()

Returns the next element in the iteration.

Returns:

the next element in the iteration

Throws:

NoSuchElementException - if the iteration has no more elements

remove

void remove()

Removes from the underlying collection the last element returned by this iterator (optional operation). This method can be called only once per call to next(). The behavior of an iterator is unspecified if the underlying collection is modified while the iteration is in progress in any way other than by calling this method.

Throws:

UnsupportedOperationException - if the remove operation is not supported by this iterator

IllegalStateException - if the next method has not yet been called, or the remove method has already been called after the last call to the next method