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

[Jim Laskey]

On Thu, 23 Feb 2023 15:52:15 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> Add the ability to repeatedly append char and CharSequence data to StringBuilder/StringBuffer.
>
> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1839:
> 
>> 1837:      * @throws StringIndexOutOfBoundsException  if the result overflows the buffer
>> 1838:      */
>> 1839:     public AbstractStringBuilder repeat(char c, int count) {
> 
> The shadowing of the count field is a hidden maintenance trap.

I know but Stuart requested it.

> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1867:
> 
>> 1865: 
>> 1866:     private AbstractStringBuilder repeatNull(int count) {
>> 1867:         if (count < 0) {
> 
> This could be implemented as `repeat("null", count)`. Its not likely to be performance sensitive and be easier to maintain.

Just being consistent with existing code.

> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1869:
> 
>> 1867:         if (count < 0) {
>> 1868:             throw new IllegalArgumentException("count is less than zero: " + count);
>> 1869:         } else if (count == 0) {
> 
> Inconsistent `if ... else if ...` structure compared to method above.

Noted. Will fix.

> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1879:
> 
>> 1877:             throw new OutOfMemoryError("Required length exceeds implementation limit");
>> 1878:         }
>> 1879:         int limit = count * length;
> 
> The meaning of limit should be consistent across uses.  Above it is an index into the buffer; here it is an offset.

Not seeing it.

> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1904:
> 
>> 1902:     public AbstractStringBuilder repeat(CharSequence cs, int count) {
>> 1903:         if (cs == null) {
>> 1904:             return repeatNull(count);
> 
> Or just replace `cs = "null";` and fall through to the rest.

Same.

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