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Java 21: records, sealed types and virtual threads v1.0.0

Use this resource to write Java 21 code using records, sealed types and virtual threads

New

  • 522 downloads
  • 201 likes
  • 180 saves

Free

Install with the CLI

In a terminal, from the folder you want:

npx --yes palatekit@latest install java-21-modern-patterns

With no option, the skill goes to ~/.agents/skills/; add --agent claude-code (or codex, cursor…) to target an agent.

First time: connect the CLI with

npx --yes palatekit@latest login

The agent models DTOs as validated records, describes closed hierarchies as sealed types and replaces thread-per-request with virtual threads. You get Java 21 code and a list of anti-patterns to avoid.

Mostly picked by

Updated November 2, 2026

Card for the “Java 21: records, sealed types and virtual threads” skill

Details

Works in
Install guides
Generates with
Your agent's model
Licence
MIT

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What you get

  • SKILL.md: three core patterns with examples
  • SKILL.md: anti-patterns to avoid

Good fit for

  • You are writing a Java service that handles many blocking calls
  • You want immutable DTOs and a closed hierarchy

Not for

    Tags

    • java
    • records
    • sealed types
    • virtual threads

    About

    You say

    “Model the payment types as a sealed type with one record per variant, then write the switch.”

    Card for the “Java 21: records, sealed types and virtual threads” skill

    Skill published by gentleman-programming under the MIT license, delivered in its original version.

    Show more

    How to use it

    1. Install the skill in your agent's skills folder
    2. Ask your agent to write Java 21 code using records, sealed types and virtual threads
    3. Review and adjust the result

    Content preview

    Files

    • LICENSE1.1 KB
    • NOTICE-PALATEKIT.md0.5 KB
    • SKILL.md2.8 KB

    Origin and licence

    Listed unmodified

    Author
    gentleman-programming
    Source
    github.com/gentleman-programming/gentleman-skills/tree/c8036a37893679dc5e942484975405d39689c63b/community/java-21
    Licence
    MIT

    Notice

    « java-21 » (gentleman-programming, MIT) livré dans sa version d'origine : fiche en français et en anglais par PalateKit.

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