On Wed, 5 Aug 2026 15:08:05 GMT, Chen Liang <[email protected]> wrote:
>> The 3 methods to determine conversions and subtyping on `java.lang.Class`, >> which are `isInstance`, `cast`, and `isAssignableFrom`, have their >> documentation from the earliest days of the Java Platform. During the >> language evolution, a lot of terms have become inaccurate, such as >> "assignment-compatible", which does not apply for primitive types, and the >> out-of-date instanceof analogy with the upcoming patterns, in `isInstance`; >> `isAssignableFrom` is not very clear about arrays; `cast` would also benefit >> from more detailed explanations. >> >> In my facelift, I moved the subtyping description to `isAssignableFrom`, and >> left the conversion stuff in `isInstance` and `cast`. I intentionally >> avoided linking to too many JLS chapters to reduce confusions. I believe in >> this shape, we have a good amount of easily comprehensible yet accurate >> specification for all 3 methods, and users are welcome to read the linked >> JLS chapters for more details and context. >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Chen Liang has updated the pull request with a new target base due to a merge > or a rebase. The incremental webrev excludes the unrelated changes brought in > by the merge/rebase. The pull request contains 13 additional commits since > the last revision: > > - Typo tweaks > - Merge branch 'master' of https://github.com/openjdk/jdk into > doc/class-casts > - Rendering updates > - More tweaks > - Merge branch 'master' of https://github.com/openjdk/jdk into > doc/class-casts > - Tweak > - Merge branch 'master' of https://github.com/openjdk/jdk into > doc/class-casts > - Stage > - Rewording from Kevin > - Non-null more straightforward than object > - ... and 3 more: https://git.openjdk.org/jdk/compare/aff316df...ee574e4f src/java.base/share/classes/java/lang/Class.java line 818: > 816: * <ul> > 817: * <li>If T is a primitive type or void, returns whether T and P are > the same. > 818: * <li>If T is a class or interface, T is a supertype of P if and > only if I think this case is not captured, right? jshell> interface SomeInterface {} | created interface SomeInterface jshell> Object.class.isAssignableFrom(SomeInterface.class) $2 ==> true ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/28684#discussion_r3757002687
