Java9OptionalTrial.java

import java.util.Optional;

public class Java9OptionalTrial {

    public static void main(String[] args) {
        new Java9OptionalTrial().ifPresentTrial();
    }

    public void ifPresentTrial() {
        present().ifPresentOrElse(
                s -> System.out.println(s),
                () -> System.out.println("not present")
        );
        notPresent().ifPresentOrElse(
                s -> System.out.println(s),
                () -> System.out.println("not present")
        );
    }

    private Optional<String> present() {
        return Optional.of("present");
    }
    
    private Optional<String> notPresent() {
        return Optional.empty();
    }
}

Result:

$ java Java9OptionalTrial
present
not present
$