PrimitiveIterator (Java SE 26 & JDK 26)
Description: declaration: module: java.base, package: java.util, interface: PrimitiveIterator
Keywords: java.util.PrimitiveIterator interface

# Interface PrimitiveIterator<T,T_CONS>

Type Parameters:
  `T` - the type of elements returned by this PrimitiveIterator. The type must be a wrapper type for a primitive type, such as `Integer` for the primitive `int` type.
  `T_CONS` - the type of primitive consumer. The type must be a primitive specialization of `Consumer` for `T`, such as `IntConsumer` for `Integer`.

All Superinterfaces:
  `Iterator<T>`

All Known Subinterfaces:
  `PrimitiveIterator.OfDouble, PrimitiveIterator.OfInt, PrimitiveIterator.OfLong`

public interface PrimitiveIterator<T,T_CONS> extends Iterator<T>
A base type for primitive specializations of `Iterator`. Specialized subtypes are provided for `int`, `long`, and `double` values.

The specialized subtype default implementations of `Iterator.next()` and `Iterator.forEachRemaining(java.util.function.Consumer)` box primitive values to instances of their corresponding wrapper class. Such boxing may offset any advantages gained when using the primitive specializations. To avoid boxing, the corresponding primitive-based methods should be used. For example, `PrimitiveIterator.OfInt.nextInt()` and `PrimitiveIterator.OfInt.forEachRemaining(java.util.function.IntConsumer)` should be used in preference to `PrimitiveIterator.OfInt.next()` and `PrimitiveIterator.OfInt.forEachRemaining(java.util.function.Consumer)`.

Iteration of primitive values using boxing-based methods `next()` and `forEachRemaining()`, does not affect the order in which the values, transformed to boxed values, are encountered.

Implementation Note:
  If the boolean system property `org.openjdk.java.util.stream.tripwire` is set to `true` then diagnostic warnings are reported if boxing of primitive values occur when operating on primitive subtype specializations.
Since:
  1.8

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Interface
  Description
  `static interface`
  `PrimitiveIterator.OfDouble`
  An Iterator specialized for `double` values.
  `static interface`
  `PrimitiveIterator.OfInt`
  An Iterator specialized for `int` values.
  `static interface`
  `PrimitiveIterator.OfLong`
  An Iterator specialized for `long` values.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `forEachRemaining(T_CONS action)`
  Performs the given action for each remaining element until all elements have been processed or the action throws an exception.

  ### Methods declared in interface Iterator

  `forEachRemaining, hasNext, next, remove`
  Modifier and Type
  Method
  Description
  `default void`
  `forEachRemaining(Consumer<? super T> 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.
  `T`
  `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).

- ## Method Details

  - ### forEachRemaining

    void forEachRemaining(T_CONS 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.

    The behavior of an iterator is unspecified if the action modifies the source of elements 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` - The action to be performed for each element
    Throws:
      `NullPointerException` - if the specified action is null