But that's a bug in the library (or code you're calling into), not a bug in how you're using it. That's the main difference in my opinion. Optional allows the

But that's a bug in the library (or code you're calling into), not a bug in how you're using it. That's the main difference in my opinion. Optional allows the code to say "I never intend to return null, only an Optional that may be nothing". In theory, a library/module/whatever that's been converted to use Optional should not have any calls that do return null. In theory, its no different than a C API that can return a size or -1 for failure. Sure, it could return -2 because the language allows it, but you shouldn't need to check for that in your code that uses it.