RFR: 8251989: Hex formatting and parsing utility

[Roger Riggs]

On Fri, 2 Oct 2020 18:12:36 GMT, Weijun Wang <weijun at openjdk.org> wrote:

>> java.util.HexFormat utility:
>> 
>>  - Format and parse hexadecimal strings, with parameters for delimiter, prefix, suffix and upper/lowercase
>>  - Static factories and builder methods to create HexFormat copies with modified parameters.
>>  - Consistent naming of methods for conversion of byte arrays to formatted strings and back: formatHex and parseHex
>>  - Consistent naming of methods for conversion of primitive types: toHexDigits... and fromHexDigits...
>>  - Prefix and suffixes now apply to each formatted value, not the string as a whole
>>  - Using java.util.Appendable as a target for buffered conversions so output to Writers and PrintStreams
>>    like System.out are supported in addition to StringBuilder. (IOExceptions are converted to unchecked exceptions)
>>  - Immutable and thread safe, a "value-based" class
>> 
>> See the [HexFormat
>> javadoc](http://cr.openjdk.java.net/~rriggs/8251989-hex-formatter/java.base/java/util/HexFormat.html) for details.
>> Review comments and suggestions welcome.
>
> src/java.base/share/classes/java/util/HexFormat.java line 213:
> 
>> 211:      * @param delimiter the {@code delimiter}, non-null, may be empty
>> 212:      * @return a copy of this {@code HexFormat} with the {@code delimiter}
>> 213:      */
> 
> Is this very useful now that we already have `ofDelimeter(String)`?

withDelimiter(delim) is there for symmetry and completeness, the same goes for withLowercase().
You could start with HexFormat.of() and then augment it withDelimiter().

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PR: https://git.openjdk.java.net/jdk/pull/482