JDK 12 RFR of JDK-8146726 : Refactor AbstractProcessor to use Set.of and related methods (original) (raw)

joe darcy joe.darcy at oracle.com
Thu Nov 29 02:09:32 UTC 2018

Hi Ron,

Adding Stuart for a collections consult; Stuart, what is the currently recommended idiom to construct a unmodifiable collection with the same elements as a existing collection? In particular, for a set of Strings is something like

    Set.of(stringSet(new String[0]))

preferred over

    Collections.unmodifiableSet(stringSet);

Assume serialization is not a concern.

On 11/27/2018 1:23 PM, Ron Shapiro wrote:

Set.of() throws if there are duplicate elements - but arrayToSet() didn't do so. Is it intended to throw if either of these take duplicates?

Good catch.

After some pondering, I think it is preferable for AbstractProcessor to not treat duplicates as an error, but to issue a warning in if duplicates are found. Arguably, it would have been reasonable to treat such condition as an error initially when the API was introduced, but adding such a check now could have some unnecessary behavioral compatibility impact. The case to add an erroneous check for options is stronger than for supported annotations because supported annotations have some additional processing if modules are not present. In more detail, with modules to fully specify an annotation type, the module name needs to be used: "mod1/foo.bar" vs "mod2/foo.bar". If such a processor is run when modules are not used, then the names are stripped to "foo.bar" in both cases and that should not be treated as an error.

Revised webrev:

    http://cr.openjdk.java.net/~darcy/8146726.3/

Will possibly update based on guidance from Stuart on the collections usage question.

Thanks,

-Joe

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