On Tue, 11 Aug 2026 19:04:11 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 out-of-date instanceof analogy with the upcoming patterns, in `isInstance`; 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 15 additional commits since > the last revision: > > - Bug spotted by Aggelos > - Merge branch 'master' of https://github.com/openjdk/jdk into > doc/class-casts > - 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 > - ... and 5 more: https://git.openjdk.org/jdk/compare/0aa8659c...725cedfc src/java.base/share/classes/java/lang/Class.java line 821: > 819: * (1) T is the same as P; (2) T is a superclass of P; (3) T is a > 820: * superinterface of P; or (4) T is the {@link Object} class, > and P is > 821: * a reference type. To make the cases non-overlapping: "T is the {@link Object} class, and P is an interface or array type" ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/28684#discussion_r3761070847
