# Iterator

public interface **Iterator**

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| Known Indirect Subclasses [ListIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/ListIterator.html)\<E\>, [PrimitiveIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.html)\<T, T_CONS\>, [PrimitiveIterator.OfDouble](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.OfDouble.html), [PrimitiveIterator.OfInt](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.OfInt.html), [PrimitiveIterator.OfLong](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.OfLong.html), [Scanner](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Scanner.html) |---|---| | [ListIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/ListIterator.html)\<E\> | An iterator for lists that allows the programmer to traverse the list in either direction, modify the list during iteration, and obtain the iterator's current position in the list. | | [PrimitiveIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.html)\<T, T_CONS\> | A base type for primitive specializations of `Iterator`. | | [PrimitiveIterator.OfDouble](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.OfDouble.html) | An Iterator specialized for `double` values. | | [PrimitiveIterator.OfInt](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.OfInt.html) | An Iterator specialized for `int` values. | | [PrimitiveIterator.OfLong](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/PrimitiveIterator.OfLong.html) | An Iterator specialized for `long` values. | | [Scanner](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Scanner.html) | A simple text scanner which can parse primitive types and strings using regular expressions. | |||

An iterator over a collection. `Iterator` takes the place of
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Enumeration.html` 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](https://developers.google.com/j2objc/javadoc/jre/technotes/guides/collections/index.html).

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/ListIterator.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Iterable.html`

### Public Method Summary

|---|---|
| void | [forEachRemaining](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html#forEachRemaining(java.util.function.Consumer<?%20super%20E>))([Consumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Consumer.html)\<? super E\> action) Performs the given action for each remaining element until all elements have been processed or the action throws an exception. |
| abstract boolean | [hasNext](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html#hasNext())() Returns `true` if the iteration has more elements. |
| abstract E | [next](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html#next())() Returns the next element in the iteration. |
| void | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html#remove())() Removes from the underlying collection the last element returned by this iterator (optional operation). |

## Public Methods

#### public void
**forEachRemaining**
([Consumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Consumer.html)\<? 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.

##### Parameters

| action | The action to be performed for each element |
|---|---|

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified action is null |
|---|---|

#### public abstract boolean
**hasNext**
()

Returns `true` if the iteration has more elements.
(In other words, returns `true` if `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html#next()` would
return an element rather than throwing an exception.)

##### Returns

- `true` if the iteration has more elements

#### public abstract E
**next**
()

Returns the next element in the iteration.

##### Returns

- the next element in the iteration

##### Throws

| [NoSuchElementException](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NoSuchElementException.html) | if the iteration has no more elements |
|---|---|

#### public 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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html#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](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/UnsupportedOperationException.html) | if the `remove` operation is not supported by this iterator |
| [IllegalStateException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalStateException.html) | 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 |
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