RFR: 8263358: Update java.lang to use instanceof pattern variable

[Patrick Concannon]

On Wed, 10 Mar 2021 15:08:53 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Hi,
>> 
>> Could someone please review my code for updating the code in the `java.lang` package to make use of the `instanceof` pattern variable?
>> 
>> Kind regards,
>> Patrick
>
> Great. I included some of these in #2300 - @mlchung has asked me to split out some of the changes in that PR to make them more focused and easier to review, so I'll just go ahead and remove the things you're patching up here.

> _Mailing list message from [Brian Goetz](mailto:brian.goetz at oracle.com) on [hotspot-compiler-dev](mailto:hotspot-compiler-dev at openjdk.java.net):_
> 
> These patches are obviously minimally correct.? However, for equals
> methods at least, I would take them one step further, from:
> 
> ??????????? if (!(o instanceof Key that)) return false;
> ??????????? //noinspection StringEquality (guaranteed interned String(s))
> ??????????? return name == that.name &&
> ?????????????????? Arrays.equals(ptypes, that.ptypes);
> 
> to
> 
> ??? return (o instanceof Key that)
> ??????? && name == that.name
> ??????? && Arrays.equals(ptypes, that.ptypes);
> 
> The use of "if it's not, return false" is a holdover from when we
> couldn't express this as a single expression (which is almost always
> preferable), which means we had to fall back to control flow.? Now we
> don't have to.
> 
> On 3/10/2021 8:04 AM, Patrick Concannon wrote:

Thanks for the suggestion, Brian. I've done this now and it can be viewed in commit e9d9131

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PR: https://git.openjdk.java.net/jdk/pull/2913