Java .spliterator()

In Java, a Spliterator is an interface introduced in Java 8 as part of the Stream API(Application Programming Interface). It provides a way to perform parallel traversal over the elements of a source, such as an array, a generator function, etc.

The ArrayList class in Java also implements the Spliterator interface using the .spliterator() method. This method returns a Spliterator over the elements in ArrayList. It is considered a better way to iterate over elements as it gives more control over them.

The .spliterator() method can be combined with a number of other methods:

• .tryAdvance(): This method is used to iterate elements separately in several threads to enable parallel processing.
• .forEachRemaining(): This method is used to iterate elements consecutively in a single thread.
• .trySplit(): This method splits the obtained Spliterator into separate parts to facilitate parallel processing.

Syntax

public Spliterator<T> split = list.spliterator()

Here, T represents the type of elements in the list collection. For example, if the collection is of type List<String>, i.e., it contains String elements, then T would be String.

Examples

Example 1

In this example, the .spliterator() method is called on the ArrayList instance named arrayList to obtain a Spliterator for its elements:

import java.util.ArrayList;
import java.util.Spliterator;

public class ArrayListSpliteratorExample {
  public static void main(String[] args) {

    // Creating an ArrayList
    ArrayList<String> arrayList = new ArrayList<>();
    arrayList.add("Java");
    arrayList.add("Python");
    arrayList.add("C++");
    arrayList.add("JavaScript");

    // Obtaining a Spliterator from ArrayList
    Spliterator<String> spliterator = arrayList.spliterator();

    // // Iterating elements using the .forEachRemaining() method
    spliterator.forEachRemaining(System.out::println);
  }
}

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The output of the mentioned code is as follows:

Java
Python
C++
JavaScript

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Example 2

In this example, the .trySplit() method is used to split the Spliterator into two parts. Then, the .forEachRemaining() method is used to traverse over the elements on each part one-by-one:

import java.util.ArrayList;
import java.util.List;
import java.util.Spliterator;

public class ArrayListSpliteratorExample {
  public static void main(String[] args) {

    // Creating an ArrayList
    ArrayList<String> arrayList = new ArrayList<>();
    arrayList.add("Ruby");
    arrayList.add("Rust");
    arrayList.add("PHP");
    arrayList.add("Go");

    // Obtaining a Spliterator from ArrayList
    Spliterator<String> spliterator = arrayList.spliterator();

    // Splitting the Spliterator
    Spliterator<String> secondHalf = spliterator.trySplit();

    System.out.println("First Half:");

    // Iterating elements using the .forEachRemaining() method
    spliterator.forEachRemaining(System.out::println);

    System.out.println("Second Half:");

    secondHalf.forEachRemaining(System.out::println);
  }
}

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The output of the mentioned code is as follows:

First Half:
PHP
Go
Second Half:
Ruby
Rust

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