Claude
ff6130bede
Payment model, permits and the three modifiers, default-branch trap, generic and recursive hierarchies, visitor comparison, run-time enforcement, modules. Transcripts from JDK 21, 25 and 27. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01TF9JWFvJSNm6HVzswzZU5a
922 B
922 B
sealed — Sealed classes and interfaces
Companion code for the ankurm.com article Sealed Classes and Interfaces: Modelling Domains with Exhaustive switch. The explanation lives in the article; this folder holds the runnable sources and the transcripts they produced.
JDK25=/path/to/jdk-25 JDK27=/path/to/jdk-27 [JDK21=/path/to/jdk-21] ./run.sh # regenerates output/*.txt
src/compiles and runs unchanged on 21, 25 and 27: thePaymentmodel, the three subclass modifiers, generic and recursive hierarchies, thedefaulttrap and a visitor for comparison.broken/fails to compile on purpose (one rule per file).sep/shows what the JVM itself enforces when a class file disagrees with the sealed type it claims to extend.multi/is a named module, the only place a sealed hierarchy may span packages.
Tested on Temurin 25.0.4.1+1 and 27+35, and OpenJDK 21.0.10 as the baseline.