Java 17: implementing Converting Optional<List<T>> to List<T> with Stream API
I just started working with I need help solving I'm trying to implement I'm attempting to set up I tried several approaches but none seem to work..... I've looked through the documentation and I'm still confused about I'm currently working on a Java 17 application where I need to convert an `Optional<List<String>>` into a `List<String>`. I've been trying to leverage the Stream API, but I'm running into some unexpected behavior. Here's what I've tried: ```java Optional<List<String>> optionalList = Optional.of(Arrays.asList("apple", "banana", "cherry")); List<String> result = optionalList.stream() .flatMap(Collection::stream) .collect(Collectors.toList()); ``` The above code works fine if the `Optional` contains a list, resulting in a list of strings. However, when the `Optional` is empty, I expected `result` to be an empty list. Instead, I get a `NoSuchElementException`. What I want is to safely handle the empty case and ensure that `result` is an empty list instead. After some research, I tried using `orElseGet` to provide an empty list as a default: ```java List<String> result = optionalList.orElseGet(Collections::emptyList); ``` However, this approach bypasses the Stream API completely. I would like to combine the benefits of the Stream API with a safe handling of the empty `Optional`. Is there a more elegant way to achieve this? Am I missing something in my stream processing that could guide to handle the empty case effectively without throwing exceptions? I'm working on a web app that needs to handle this. What am I doing wrong? What am I doing wrong? I'm using Java LTS in this project. Any advice would be much appreciated. What would be the recommended way to handle this?