How to get a stream from Optional class in Java 9?

The Optional class provides a container that may or may not contain a non-null value. It has been introduced in Java 8 to reduce the number of places in the code where a NullPointerException has generated. Java 9 added three methods: ifPresentOrElse(), or(), and stream(), which helps us deal with default values.

In the below example, we can get a stream from Optional class using Person class

Example

import java.util.Optional; import java.util.stream.Stream; public class OptionalTest {    public static void main(String args[]) {       getPerson().stream()                  .map(Person::getName)                  .map("Jai "::concat)                  .forEach(System.out::println);       getEmptyPerson().stream()                       .map(Person::getName)                       .map("Jai "::concat)                       .forEach(System.out::println);    }    private static Optional<Person> getEmptyPerson() {       return Optional.empty();    }    private static Optional<Person> getPerson() {       return Optional.of(new Person("Adithya"));    }    static class Person {       private String name;       public Person(String name) {          this.name = name;       }       public String getName() {          return name;       }       public void setName(String name) {          this.name = name;       }    } }

Output

Jai Adithya