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javademos/sealed/README.md
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Claude d2c1efc2c4 sealed: add release-level and Jackson 3.2.3 transcripts
09 shows which language level each sealed feature needs; 10 runs the Payment model through Jackson 3 (jars fetched and sha1-checked, not committed).

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01TF9JWFvJSNm6HVzswzZU5a
2026-09-24 12:08:23 +00:00

1.1 KiB

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: the Payment model, the three subclass modifiers, generic and recursive hierarchies, the default trap 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.
  • jackson/ runs the same Payment through Jackson 3.2.3 (./jackson/fetch.sh downloads and sha1-checks the three jars from Maven Central; they are not committed).
  • 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.