RFR: 8057113: (fs) Path should have a method to obtain the filename extension [v16]

[Mark Reinhold]

On Thu, 28 Jul 2022 23:12:32 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Resurrection of the proposal to add a method to obtain the filename extension originated in PR [2319](https://github.com/openjdk/jdk/pull/2319).
>
> Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8057113: Update specification, implementation, and test

Changes requested by mr (Lead).

src/java.base/share/classes/java/nio/file/Path.java line 261:

> 259:     /**
> 260:      * Returns the file name extension of this path as a {@code String}. The
> 261:      * extension is defined to be the portion of the

Omit "defined to be"; it's redundant.

src/java.base/share/classes/java/nio/file/Path.java line 262:

> 260:      * Returns the file name extension of this path as a {@code String}. The
> 261:      * extension is defined to be the portion of the
> 262:      * {@link #getFileName file name} string after the last dot ('.'). All

`{@linkplain #getFileName file name}`

src/java.base/share/classes/java/nio/file/Path.java line 263:

> 261:      * extension is defined to be the portion of the
> 262:      * {@link #getFileName file name} string after the last dot ('.'). All
> 263:      * leading dots in the string are ignored. If the extension is missing,

Simplify `All leading` to `Leading`.

Change `the extension is missing` (which suggests an error) to `there is no extension`.

src/java.base/share/classes/java/nio/file/Path.java line 268:

> 266:      * string does not contain a dot, or only the first character is a dot.
> 267:      * If the last character is a dot but some other character is not, then
> 268:      * the extension is the {@link String#isEmpty() empty} string.

The term "dot" is imprecise. Consider saying `period character ('.', U+002E FULL STOP)` on first use (to be consistent with [other specifications][jlc]), and `period character` thereafter.

[jlc]: https://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/lang/Character.html#isWhitespace(char)

-------------

PR: https://git.openjdk.org/jdk/pull/8066