RFR: 8298318: (fs) APIs for handling filename extensions [v2]

[Anthony Vanelverdinghe]

On Wed, 22 Nov 2023 17:37:57 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> I thought we were moving away from the addExtension/removeExtension methods to the recommendation for `withExtension` and `withoutExtension`.

My bad. The point about it being impossible(?) to specify an invariant with these methods still holds though.

> The APIs should not require the developer to be aware of and code around OS specific details. For an outlier like ".gitconfig" they won't be using any of these functions, that's the full file name, semantically it does not have an extension and certainly one would not consider the leading "." to be the base name without the extension; that would be a directory. Even if the "." were considered to be part of the extension, that would leave the empty string as the base and is not meaningful if its empty.

`.gitconfig` was a bad example. Consider `Path.of("C:\\Music\.mp3").getExtension()` instead. What I'm advocating, is that this should result in an extension of `mp3`, because that's what Windows users expect (& what I would expect if I were to use this API). On Windows, it's perfectly acceptable for the base name to be empty. (In an ideal world, cross-platform applications like Git would adapt to OS-specific conventions and the file would be named `gitconfig` on Windows.)

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PR Comment: https://git.openjdk.org/jdk/pull/16226#issuecomment-1823894253