It’s confusing that

Flow.toList()

closes the Flow but

Stream.toList()

doesn’t close the Stream. Is that inconsistency intentional?

What do you mean by "closes"? Flows can't be closed.

I’m not sure how exactly it works or is called, but Flows can free resources upon cancelation or completion, don’t they? I don’t have to take care of that, e.g. I don’t have to “close” a Flow for reading a file in order to close the file descriptor. With Stream I’ll have to do that, even after a terminal operation like

.toList()

.

Ah I think I see what you mean. Once a Flow is collected (e.g. calling

toList()

) it must be completely collected (or cancelled). With this rule, a

Flow

can hold on to resources once collection starts and release them upon completion/cancellation. Streams on the other hand, don't have to be completed after iteration begins, so the close method is used to signal a cancellation (I guess). Disclaimer: Haven't properly used Streams.

Yes, Stream must be closed even after a terminal operation has completed. Hence the confusion when using Kotlin’s

toList()

on each.

OH! You are referring to Kotlin's

toList()

, I thought it was a special java function. Can you point me to the

toList()

function? I don't think it's the same function for both objects.

It’s not the same function. It’s just very similar. In both cases you have a stream of value and in one case Kotlin’s

toList()

will close resources, in the other case it won’t. I think it’s a problem with Streams, but because they’re so similar and both coming from Kotlin, it’s still confusing.