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