Finding a more functional approach using Java Optional?

Question

I'm trying my hand at using Optional as much as I can over normal null checks; and I ran into a suggestion by my IDE (IntelliJ):

Can be replaced by a singular expression in functional style.

Here is the code in question, the line in question:

Entry entry = maybeBytes.isPresent() ? Entry.deserialize(maybeBytes.get()) : new Entry();

I've looked a bit here, but couldn't find a usage or at least see one that would fit my case here. I'm pretty new to the lambda features.

Answer 1

How about:

Entry entry = maybeBytes.map(Entry::deserialize).orElseGet(Entry::new);

If maybeBytes contains a value, it will be passed to the function you provide to map(), and you'll get an Optional<Entry> with the result (and if maybeBytes was empty, you'll get an empty Optional<Entry>). orElseGet() will give you the contents of the Optional<Entry> if it's nonempty, and otherwise, it will give you the result of evaluating the function you pass to it (in this case, the constructor of Entry).