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Java 8 - Optional - Flat Map





  • When a transformation on an optional transforms such optional to an optional of optional, we use flatMap to flatten the result back to an optional.

@Slf4j
public class FlatMap {

   static Optional<Person> dj = Optional.of(new Person("DJ", "JimmyJack"));

   public static void main(String[] args) {

     log.info("flatMap on an option flattens the result to an optional value: " +

      dj.flatMap(person -> {

       if(person.getFirstName().equals("Paul"))
        return Optional.of(new Person("DJ_2", "JimmyJack"));

       return dj;
     })
    );

   }
}
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