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