Optional streams

Two of Java 8’s tentpole features are optionals and streams. Unfortunately, streaming optionals often involves code like:

Set<Optional<MyType>> mySet = ...
mySet.stream()
  .filter(Optional::isPresent)
  .map(Optional::get)
  .map(MyType::functionICareAbout)
  ...

Requiring two lines to unwrap optionals and discard the empty ones isn’t the end of the world, but it has gotten nicer in Java 9. The Optional::stream method transforms an optional into a stream that has either zero or one elements. Therefore, we can write code like:

Set<Optional<MyType>> mySet = ...
mySet.stream()
  .flatMap(Optional::stream)
  .map(MyType::functionICareAbout)
  ...

Not life changing, but a little bit nicer than before.