Optional stream() method in Java with examples

The stream() method of java.util.Optional class in Java is used to get the sequential stream of the only value present in this Optional instance. If there is no value present in this Optional instance, then this method returns returns an empty Stream.

Syntax:

public Stream<T> stream()

Parameters: This method do not accept any parameter.



Return value: This method returns the sequential stream of the only value present in this Optional instance. If there is no value present in this Optional instance, then this method returns an empty Stream.

Below programs illustrate stream() method:

Note: Below programs require JDK 9 and above to execute.

Program 1:

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java program to demonstrate
// Optional.stream() method
  
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // create a Optional
        Optional<Integer> op
            = Optional.of(9455);
  
        // print value
        System.out.println("Optional: "
                           + op);
  
        // get the Stream
        System.out.println("Getting the Stream:");
        op.stream().forEach(System.out::println);
    }
}

chevron_right


Output:

Optional: Optional[9455]
Getting the Stream:
9455

Program 2:

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java program to demonstrate
// Optional.stream() method
  
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // create a Optional
        Optional<Integer> op
            = Optional.empty();
  
        // print value
        System.out.println("Optional: "
                           + op);
  
        try {
  
            // get the Stream
            System.out.println("Getting the Stream:");
            op.stream().forEach(System.out::println);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

chevron_right


Output:

Optional: Optional.empty
Getting the Stream:

Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Optional.html#stream–



My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.