LongStream findAny() with examples

LongStream findAny() returns an OptionalLong (a container object which may or may not contain a non-null value) describing some element of the stream, or an empty OptionalLong if the stream is empty.

Syntax :

OptionalLong findAny() 

Parameters :

1. OptionalLong : A container object which may or may not contain a non-null value.

Return Value : The function returns an OptionalLong describing some element of this stream, or an empty OptionalLong if the stream is empty.

Note : findAny() is a terminal-short-circuiting operation of Stream interface. This method returns any first element satisfying the intermediate operations. This is a short-circuit operation because it just needs ‘any’ first element to be returned and terminate the rest of the iteration.

Example 1 : findAny() method on Long Stream.

// Java code for LongStream findAny()
// which returns an OptionalLong describing
// some element of the stream, or an
// empty OptionalLong if the stream is empty.
import java.util.*;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating an LongStream
        LongStream stream = LongStream.of(6L, 7L, 8L, 9L);

        // Using LongStream findAny() to return
        // an OptionalLong describing some element
        // of the stream
        OptionalLong answer = stream.findAny();

        // if the stream is empty, an empty
        // OptionalLong is returned.
        if (answer.isPresent()) {
            System.out.println(answer.getAsLong());
        }
        else {
            System.out.println("no value");
        }
    }
}

Output :

6

Note : The behavior of LongStream findAny() operation is explicitly non-deterministic i.e, it is free to select any element in the stream. Multiple invocations on the same source may not return the same result.

Example 2 : findAny() method to return the elements divisible by 4, in a non-deterministic way.

// Java code for LongStream findAny()
// which returns an OptionalLong describing
// some element of the stream, or an
// empty OptionalLong if the stream is empty.
import java.util.OptionalLong;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating an LongStream
        LongStream stream = LongStream.of(4L, 5L, 8L, 10L, 12L, 16L)
                                .parallel();

        // Using LongStream findAny().
        // Executing the source code multiple times
        // may not return the same result.
        // Every time you may get a different
        // value which is divisible by 4.
        stream = stream.filter(num -> num % 4 == 0);

        OptionalLong answer = stream.findAny();
        if (answer.isPresent()) {
            System.out.println(answer.getAsLong());
        }
    }
}

Output :

16