ISpliterator Interface

Definition

[Android.Runtime.Register("java/util/Spliterator", "", "Java.Util.ISpliteratorInvoker", ApiSince=24)]
[Java.Interop.JavaTypeParameters(new System.String[] { "T" })]
public interface ISpliterator : Android.Runtime.IJavaObject, IDisposable, Java.Interop.IJavaPeerable

[<Android.Runtime.Register("java/util/Spliterator", "", "Java.Util.ISpliteratorInvoker", ApiSince=24)>]
[<Java.Interop.JavaTypeParameters(new System.String[] { "T" })>]
type ISpliterator = interface
    interface IJavaObject
    interface IDisposable
    interface IJavaPeerable

Derived

Java.Util.Spliterators.AbstractSpliterator

Attributes

RegisterAttribute JavaTypeParametersAttribute

Implements

IJavaObject IJavaPeerable IDisposable

Remarks

An object for traversing and partitioning elements of a source. The source of elements covered by a Spliterator could be, for example, an array, a Collection, an IO channel, or a generator function.

A Spliterator may traverse elements individually (#tryAdvance tryAdvance()) or sequentially in bulk (#forEachRemaining forEachRemaining()).

A Spliterator may also partition off some of its elements (using #trySplit) as another Spliterator, to be used in possibly-parallel operations. Operations using a Spliterator that cannot split, or does so in a highly imbalanced or inefficient manner, are unlikely to benefit from parallelism. Traversal and splitting exhaust elements; each Spliterator is useful for only a single bulk computation.

A Spliterator also reports a set of #characteristics() of its structure, source, and elements from among #ORDERED, #DISTINCT, #SORTED, #SIZED, #NONNULL, #IMMUTABLE, #CONCURRENT, and #SUBSIZED. These may be employed by Spliterator clients to control, specialize or simplify computation. For example, a Spliterator for a Collection would report SIZED, a Spliterator for a Set would report DISTINCT, and a Spliterator for a SortedSet would also report SORTED. Characteristics are reported as a simple unioned bit set.

Some characteristics additionally constrain method behavior; for example if ORDERED, traversal methods must conform to their documented ordering. New characteristics may be defined in the future, so implementors should not assign meanings to unlisted values.

"binding">A Spliterator that does not report <c>IMMUTABLE</c> or <c>CONCURRENT</c> is expected to have a documented policy concerning: when the spliterator <em>binds</em> to the element source; and detection of structural interference of the element source detected after binding. A <em>late-binding</em> Spliterator binds to the source of elements at the point of first traversal, first split, or first query for estimated size, rather than at the time the Spliterator is created. A Spliterator that is not <em>late-binding</em> binds to the source of elements at the point of construction or first invocation of any method. Modifications made to the source prior to binding are reflected when the Spliterator is traversed. After binding a Spliterator should, on a best-effort basis, throw ConcurrentModificationException if structural interference is detected. Spliterators that do this are called <em>fail-fast</em>. The bulk traversal method (#forEachRemaining forEachRemaining()) of a Spliterator may optimize traversal and check for structural interference after all elements have been traversed, rather than checking per-element and failing immediately.

Spliterators can provide an estimate of the number of remaining elements via the #estimateSize method. Ideally, as reflected in characteristic #SIZED, this value corresponds exactly to the number of elements that would be encountered in a successful traversal. However, even when not exactly known, an estimated value may still be useful to operations being performed on the source, such as helping to determine whether it is preferable to split further or traverse the remaining elements sequentially.

Despite their obvious utility in parallel algorithms, spliterators are not expected to be thread-safe; instead, implementations of parallel algorithms using spliterators should ensure that the spliterator is only used by one thread at a time. This is generally easy to attain via <em>serial thread-confinement</em>, which often is a natural consequence of typical parallel algorithms that work by recursive decomposition. A thread calling #trySplit() may hand over the returned Spliterator to another thread, which in turn may traverse or further split that Spliterator. The behaviour of splitting and traversal is undefined if two or more threads operate concurrently on the same spliterator. If the original thread hands a spliterator off to another thread for processing, it is best if that handoff occurs before any elements are consumed with #tryAdvance(Consumer) tryAdvance(), as certain guarantees (such as the accuracy of #estimateSize() for SIZED spliterators) are only valid before traversal has begun.

Primitive subtype specializations of Spliterator are provided for OfInt int, OfLong long, and OfDouble double values. The subtype default implementations of Spliterator#tryAdvance(java.util.function.Consumer) and Spliterator#forEachRemaining(java.util.function.Consumer) box primitive values to instances of their corresponding wrapper class. Such boxing may undermine any performance advantages gained by using the primitive specializations. To avoid boxing, the corresponding primitive-based methods should be used. For example, Spliterator.OfInt#tryAdvance(java.util.function.IntConsumer) and Spliterator.OfInt#forEachRemaining(java.util.function.IntConsumer) should be used in preference to Spliterator.OfInt#tryAdvance(java.util.function.Consumer) and Spliterator.OfInt#forEachRemaining(java.util.function.Consumer). Traversal of primitive values using boxing-based methods #tryAdvance tryAdvance() and #forEachRemaining(java.util.function.Consumer) forEachRemaining() does not affect the order in which the values, transformed to boxed values, are encountered.

Added in 1.8.

Java documentation for java.util.Spliterator.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Properties

Methods

Extension Methods

Applies to