Using Optional as a better alternative to null - Java 8 in Action: Lambdas, Streams, and Functional-Style Programming - page 298

 Java 8 introduces the class java.util.Optional<T> to model the presence or absence of a value.
 You can create Optional objects with the static factory methods Optional.empty , Optional.of , and
Optional.ofNullable .
 The Optional class supports many methods such as map , flatMap , and filter , which are
conceptually similar to the methods of a stream.
 Using Optional forces you to actively unwrap an optional to deal with the absence of a value; as a
result, you protect your code against unintended null pointer exceptions.
 Using Optional can help you design better APIs in which, just by reading the signature of a method,
users can tell whether to expect an optional value.