RFR (JDK11) 8137326: Methods for comparing CharSequence, StringBuilder, and StringBuffer

[Joe Wang]

Thanks Jason. Will update that accordingly.

Best,
Joe

On 2/2/2018 11:22 AM, Jason Mehrens wrote:
> Joe,
>
> The identity check in CS.compare makes sense.  However, it won't be null hostile if we call CS.compare(null, null) and that doesn't seem right.
> Usually when writing comparator classes I end up with:
> ===
> if (Objects.requireNonNull(o1) == Objects.requireNonNull(o2)) {
>      return 0;
> }
> ===
>
> Jason
> ________________________________________
> From: core-libs-dev <core-libs-dev-bounces at openjdk.java.net> on behalf of Joe Wang <huizhe.wang at oracle.com>
> Sent: Friday, February 2, 2018 1:01 PM
> To: core-libs-dev
> Subject: Re: RFR (JDK11) 8137326: Methods for comparing CharSequence, StringBuilder, and StringBuffer
>
> Hi,
>
> Thanks all for comments and suggestions. I've updated the webrev. Please
> review.
>
> JBS: https://bugs.openjdk.java.net/browse/JDK-8137326
> webrev: http://cr.openjdk.java.net/~joehw/jdk11/8137326/webrev/
>
> Thanks,
> Joe
>
> On 1/31/2018 9:31 PM, Joe Wang wrote:
>> Hi Tagir,
>>
>> Thanks for the comment. I will consider adding that to the javadoc
>> emphasizing that the comparison is performed from 0 to length() - 1 of
>> the two sequences.
>>
>> Best,
>> Joe
>>
>> On 1/29/18, 8:07 PM, Tagir Valeev wrote:
>>> Hello!
>>>
>>> An AbstractStringBuilder#compareTo implementation is wrong. You cannot
>>> simply compare the whole byte array. Here's the test-case:
>>>
>>> public class Test {
>>>     public static void main(String[] args) {
>>>       StringBuilder sb1 = new StringBuilder("test1");
>>>       StringBuilder sb2 = new StringBuilder("test2");
>>>       sb1.setLength(4);
>>>       sb2.setLength(4);
>>>       System.out.println(sb1.compareTo(sb2));
>>> System.out.println(sb1.toString().compareTo(sb2.toString()));
>>>     }
>>> }
>>>
>>> We truncated the stringbuilders making their content equal, so
>>> sb1.toString().compareTo(sb2.toString()) is 0, but compareTo compares
>>> the original content (before the truncation) as truncation, of course,
>>> does not zero the truncated bytes, neither does it reallocate the
>>> array (unless explicitly asked via trimToSize).
>>>
>>> With best regards,
>>> Tagir Valeev.
>>>
>>>
>>> On Fri, Jan 26, 2018 at 10:00 AM, Joe Wang<huizhe.wang at oracle.com>
>>> wrote:
>>>> Hi,
>>>>
>>>> Adding methods for comparing CharSequence, StringBuilder, and
>>>> StringBuffer.
>>>>
>>>> The Comparable implementations for StringBuilder/Buffer are similar
>>>> to that
>>>> of String, allowing comparison operations between two
>>>> StringBuilders/Buffers, e.g.
>>>> aStringBuilder.compareTo(anotherStringBuilder).
>>>> For CharSequence however, refer to the comments in JIRA, a static
>>>> method
>>>> 'compare' is added instead of implementing the Comparable interface.
>>>> This
>>>> 'compare' method may take CharSequence implementations such as String,
>>>> StringBuilder and StringBuffer, making it possible to perform
>>>> comparison
>>>> among them. The previous example for example is equivalent to
>>>> CharSequence.compare(aStringBuilder, anotherStringBuilder).
>>>>
>>>> Tests for java.base have been independent from each other. The new
>>>> tests are
>>>> therefore created to have no dependency on each other or sharing any
>>>> code.
>>>>
>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8137326
>>>> webrev: http://cr.openjdk.java.net/~joehw/jdk11/8137326/webrev/
>>>>
>>>> Thanks,
>>>> Joe