Java 8 - general practice using Optional

0. Never, ever use null for an Optional variable.\

1. Optional should be only used as a return value.\

   never use it for a field in Class and a method parameter.\
   never use it in collections

2. Never try to call .get() method on an Optional.\

if it is a situation to get a value, ifPresent, map and orElse() family can solve this problem .

3. Remember Optional is not Serializable.

Note)\
Java 9 will introduce the following new method\

Optional.stream()
Optional.ifPresentOrElse()
Optional.or()