Java ArrayList spliterator() Method

Example

Use a Spliterator to loop through items in a list:

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

public class Main {
  public static void main(String[] args) {
  
    // Make a collection
    ArrayList<String> cars = new ArrayList<String>();
    cars.add("Volvo");
    cars.add("BMW");
    cars.add("Ford");
    cars.add("Mazda");
  
    // Get the spliterator and split it
    Spliterator<String> it1 = cars.spliterator();
    Spliterator<String> it2 = it1.trySplit();
    
    // Loop through the first spliterator
    System.out.println("First spliterator");
    while( it1.tryAdvance( (n) -> { System.out.println(n); } ) );
    
    // Loop through the second spliterator
    System.out.println("\nSecond spliterator");
    while( it2.tryAdvance( (n) -> { System.out.println(n); } ) );
  }
}

Try it Yourself »

Note: The syntax while( it1.tryAdvance( (n) -> { System.out.println(n); } ) ); is equivalent to:

boolean x = it1.tryAdvance( (n) -> { System.out.println(n); });
while(x) {
  x = it1.tryAdvance( (n) -> { System.out.println(n); });
}

Definition and Usage

The spliterator() method returns a Spliterator for the list.

A spliterator is a special type of iterator. To learn how to use iterators, see our Java Iterator tutorial.

The Spliterator is considerably different from an ordinary iterator. The purpose of a spliterator is to separate a collection into smaller pieces so that each piece can be processed by a separate thread. The Spliterator interface has two important methods:

trySplit() - Returns a new spliterator which can iterate through (usually and approximately) half of the elements that the original spliterator has access to, while the original spliterator can iterate through the remaining half.
tryAdvance(Consumer action) - Moves to the next item that is available to the spliterator and tries to perform an action on it. If there is no next item then it returns false. The action can be defined by a lambda expression.