RFR: JDK-8302323 Add repeat methods to StringBuilder/StringBuffer [v3]

[Tagir F. Valeev]

On Mon, 27 Feb 2023 13:30:47 GMT, Jim Laskey <jlaskey at openjdk.org> wrote:

>> Add the ability to repeatedly append char and CharSequence data to StringBuilder/StringBuffer.
>
> Jim Laskey has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Optimize for empty CharSequence

src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1903:

> 1901:             throw new OutOfMemoryError("Required length exceeds implementation limit");
> 1902:         }
> 1903:         int total = count * length;

We may avoid division if we use the long type:


long totalLong = ((long) count) * length;
if (totalLong > Integer.MAX_VALUE - offset) {
    throw new OutOfMemoryError("Required length exceeds implementation limit");
}
int total = (int) totalLong;


Should be faster.

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PR: https://git.openjdk.org/jdk/pull/12728