Added in API level 1

Iterator

interface Iterator<E : Any!>
java.util.Iterator

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.

Summary

Public methods
open Unit
forEachRemaining(action: Consumer<in E>)

Performs the given action for each remaining element until all elements have been processed or the action throws an exception.

abstract Boolean

Returns true if the iteration has more elements.

abstract E

Returns the next element in the iteration.

open Unit

Removes from the underlying collection the last element returned by this iterator (optional operation).

Public methods

forEachRemaining

Added in API level 24
open fun forEachRemaining(action: Consumer<in E>): Unit

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.

The behavior of an iterator is unspecified if the action modifies the collection in any way (even by calling the remove method or other mutator methods of Iterator subtypes), unless an overriding class has specified a concurrent modification policy.

Subsequent behavior of an iterator is unspecified if the action throws an exception.

Parameters
action Consumer<in E>: The action to be performed for each element
Exceptions
java.lang.NullPointerException if the specified action is null

hasNext

Added in API level 1
abstract fun hasNext(): Boolean

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

Return
Boolean true if the iteration has more elements

next

Added in API level 1
abstract fun next(): E

Returns the next element in the iteration.

Return
E the next element in the iteration
Exceptions
java.util.NoSuchElementException if the iteration has no more elements

remove

Added in API level 1
open fun remove(): Unit

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, unless an overriding class has specified a concurrent modification policy.

The behavior of an iterator is unspecified if this method is called after a call to the forEachRemaining method.

Exceptions
java.lang.UnsupportedOperationException if the remove operation is not supported by this iterator
java.lang.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