RFR: 8305457: Implement java.io.IO [v9]

[Per Minborg]

On Mon, 13 May 2024 09:56:35 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

>> Please review this PR which introduces the `java.io.IO` top-level class and three methods to `java.io.Console` for [Implicitly Declared Classes and Instance Main Methods (Third Preview)].
>> 
>> This PR has been obtained as `git merge --squash` of a now obsolete [draft PR].
>> 
>> [Implicitly Declared Classes and Instance Main Methods (Third Preview)]: https://bugs.openjdk.org/browse/JDK-8323335
>> [draft PR]: https://github.com/openjdk/jdk/pull/18921
>
> Pavel Rappo has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 17 additional commits since the last revision:
> 
>  - Escape prompt
>  - Merge branch 'master' into 8305457-Implement-java.io.IO
>  - Clarify input charset
>  - Make IO final
>  - Fix System.console().readln(null) in jshell
>    
>    Without it, jshell hangs on me. Will think of a test.
>  - Fix typo
>  - Merge branch 'master' into 8305457-Implement-java.io.IO
>  - Simplify output.exp
>  - Cover null prompt in input tests
>  - Make input test parametric
>  - ... and 7 more: https://git.openjdk.org/jdk/compare/2f44ac18...17100ab8

src/java.base/share/classes/java/io/IO.java line 98:

> 96:      *                 or if an I/O error occurs
> 97:      */
> 98:     public static String readln(String prompt) {

Did we consider Optional<String> here? Maybe that is to complicated for an onramp?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19112#discussion_r1600145844