Using get() is just bad style and so is returning null where you could return Collections.emptyList().
Previous discussion on reddit: https://www.reddit.com/r/programming/comments/3pl7o0/java_8s...
tl;dr: use map, orElseGet, orElse
Previous discussion on reddit: https://www.reddit.com/r/programming/comments/3pl7o0/java_8s...
tl;dr: use map, orElseGet, orElse
If you don't have a default value to provide, nor an alternate code path other than "sod this, I'm bailing", get is ok. Not quite as good as using a more specific exception through orElseGet, but not bad, exactly.
Also, if you have just called isPresent (and assume your data to be immutable), then get is ok - the alternative being to manually throw something like new IllegalStateException("the impossible has happened!"), which is not that much more useful, and is a pain to have to write all the time when you know it will not get called.
I agree that you should never return null, but if get() is bad style I think you should send out that memo because I haven't yet seen codebases that agreed.
Checking presence of value of an optional is an anti-pattern, the same as doing != null checks.
You should treat Optional the same as a List type with size 1. You never check if a list is size 1 before doing map or filter.
getCharsetOpt("UTF-8")
"If it can't happen, it will".
If a function says the result is optional, then it's optional. It's not not optional because you decided it can't ever fail.