Skip to content
Related Articles

Related Articles

Improve Article

Optional stream() method in Java with examples

  • Last Updated : 30 Jul, 2019

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:




// 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);
    }
}

Output:

Optional: Optional[9455]
Getting the Stream:
9455

Program 2:




// 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);
        }
    }
}

Output:

Optional: Optional.empty
Getting the Stream:

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

Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.




My Personal Notes arrow_drop_up
Recommended Articles
Page :