What is the findAny method of Stream Interface?

The findAny method returns an Optional object with some element of the stream as a value. Optional object refers to a container object which may or may not contain a non-null value. If a value is present, isPresent() will return true, and get() will return the value.

In the case that the stream is empty, the empty Optional is returned.

Syntax

Optional<T> findAny()

The selection behavior of the element is nondeterministic and the findAny method will select any element from the stream.

The NullPointerException is thrown if the stream contains a null value and the findAny method selected that null element.

In a non-parallel operation, the findAny method will mostly return the first element from the stream, but this behavior is not guaranteed. In a parallel operation, we cannot predict which element will be returned.

Example

import java.util.Optional;
import java.util.ArrayList;
class FindAnyExample {
    public static void main( String args[] ) {
        ArrayList<Integer> numbers = new ArrayList<Integer>();
        numbers.add(1);
        numbers.add(2);
        numbers.add(3);
        System.out.println("Calling findAny method");
        Optional<Integer> anyElement  = numbers.stream().findAny();
        System.out.println("Checking if value present in optional - " + anyElement.isPresent());
        System.out.println("The picked element is " + anyElement.get());
    }
}

In the code above, we have:

  • Created an ArrayList with elements:
1,2,3
  • Then, we created a stream from the ArrayList with the stream() method.
numbers.stream() // returns numbers ArrayList as Stream

  • After we converted into stream, we called the findAny method. The findAny method will return any elementin most cases it returns the first element from the stream as an Optional object.

  • We used the isPresent() method to check if the returned Optional object contains a value, which will return true if the value present in the Optional.

  • At last, the value from the Optional is taken through the get method, and prints the element selected by the findAny method.

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