RFR: 8197594 - String and character repeat

[Brian Goetz]

I suggest merging 1 and 4 by making it an instance method on CS with a default in CS and an override on string and string builder?

Sent from my MacBook Wheel

> On Feb 15, 2018, at 9:20 AM, Jim Laskey <james.laskey at oracle.com> wrote:
> 
> This is a pre-CSR code review [1] for String repeat methods (Enhancement).
> 
> The proposal is to introduce four new methods;
> 
> 1. public String repeat(final int count)
> 2. public static String repeat(final char ch, final int count)
> 3. public static String repeat(final int codepoint, final int count)
> 4. public static String repeat(final CharSequence seq, final int count)
> 
> For the sake of transparency, only 1 is necessary, 2-4 are convenience methods.
> In the case of 2, “*”.repeat(10) performs as well as String.repeat(‘*’, 10).
> 3 and 4 convert to String before calling 1.
> 
> Performance runs with jmh (results as comment in [2]) show that these
> methods are significantly faster that StringBuilder equivalents.
> - fewer memory allocations
> - fewer char to byte array conversions
> - faster pyramid replication vs O(N) copying
> 
> I left StringBuilder out of scope. It falls under the category of
> Appendables#append with repeat. A much bigger project.
> 
> All comments welcome. Especially around the need for convenience
> methods, the JavaDoc content and expanding the tests.
> 
> — Jim
> 
> [1] webrev: http://cr.openjdk.java.net//oj/home/jlaskey/8197594/webrev-00
> [2] jbs: https://bugs.openjdk.java.net/browse/JDK-8197594
>