程序包 java.util

接口 Iterator<E>

类型参数:

E - the type of elements returned by this iterator

所有已知子接口:

ListIterator<E>, PrimitiveIterator<T,T_CONS>, PrimitiveIterator.OfDouble, PrimitiveIterator.OfInt, PrimitiveIterator.OfLong, XMLEventReader

所有已知实现类:

Scanner

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.

从以下版本开始:

1.2

另请参阅:

Collection, ListIterator, Iterable

方法概要

限定符和类型	方法	说明
default void	forEachRemaining(Consumer<? super E> action)	Performs the given action for each remaining element until all elements have been processed or the action throws an exception.
boolean	hasNext()	Returns true if the iteration has more elements.
E	next()	Returns the next element in the iteration.
default void	remove()	Removes from the underlying collection the last element returned by this iterator (optional operation).

方法详细资料

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.)

返回:

true if the iteration has more elements

next

E next()

Returns the next element in the iteration.

返回:

the next element in the iteration

抛出:

NoSuchElementException - if the iteration has no more elements

remove

default 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.

抛出:

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

forEachRemaining

default void forEachRemaining(Consumer<? super E> action)

Performs the given action for each remaining element until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller.

参数:

action - The action to be performed for each element

抛出:

NullPointerException - if the specified action is null

从以下版本开始:

1.8