RFR: 8354724: BufferedReader readAllLines and readString methods [v14]

[Alan Bateman]

On Sat, 3 May 2025 09:30:17 GMT, Markus KARG <duke at openjdk.org> wrote:

>> src/java.base/share/classes/java/io/Reader.java line 213:
>> 
>>> 211:             public String readAllChars() throws IOException {
>>> 212:                 ensureOpen();
>>> 213:                 return cs.toString().substring(next);
>> 
>> Your change implies creating a full-length string *first* (including cyoping and compression), just to strip it down to a smaller one *later*. It would be more efficient to *first* strip it down, and compression into a `String` *afterwards*. Imagine a huge `cs` with `next` being near to `length()`, and you see the difference in efficiency! 🙂 
>> 
>> `cs.subSequence(next, cs.length()).toString()`
>> 
>> (Edited my proposal to be more correct.)
>
> Oh, and we should set `next` afterwards, so the `Reader` knows that the end of the sequence is reached:
> 
> 
> public String readAllChars() throws IOException {
>     ensureOpen();
>     var len = cs.length();
>     var remainder = cs.subSequence(next, len);
>     next = len;
>     return remainder.toString();
> }
> 
> 
> (Edited my proposal to be a bit more concurrency-friendly and correct.)

Probably best to ignore the implementation details as the discussions on what methods to expose, and where, is still going on. It was probably a bit premature to create the PR without getting agreement on the API first.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/24728#discussion_r2072521725