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 |
hasNext()Returns |
| abstract E |
next()Returns the next element in the iteration. |
| open Unit |
remove()Removes from the underlying collection the last element returned by this iterator (optional operation). |
Public methods
forEachRemaining
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
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
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
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 |