RFR: 8266571: Sequenced Collections

[Stuart Marks]

On Tue, 12 Apr 2022 19:55:13 GMT, Eamonn McManus <emcmanus at openjdk.org> wrote:

>> PR for Sequenced Collections implementation.
>
> src/java.base/share/classes/java/util/LinkedHashMap.java line 604:
> 
>> 602:      * @return a set view of the keys contained in this map
>> 603:      */
>> 604:     public SequencedSet<K> keySet() {
> 
> Changing the return type means that subclasses of `LinkedHashMap` that override `keySet()` will no longer compile, unless they also change the return type.

Yes. Previously compiled binaries will also throw `NoSuchMethodError` if they call `super.keySet()`. Clearly these are incompatibilities; the question is whether they are severe enough to warrant pursuing a different approach. If you have any thoughts about how to assess the severity of this change, please let me know.

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PR Review Comment: https://git.openjdk.org/jdk/pull/7387#discussion_r848945910