
141-java-refactoring-with-modern-features
Use when you need to refactor Java code to adopt modern Java features (Java 8+) — including migrating anonymous classes to lambdas, replacing Iterator loops with Stream API, adopting Optional for null safety, switching from legacy Date/Calendar to java.time, using collection factory methods, applying text blocks, var inference, or leveraging Java 25 features like flexible constructor bodies and module import declarations. This should trigger for requests such as Review Java code for modern Java development; Apply best practices for modern Java development in Java code; Modernize Java code with records pattern matching or switch expressions; Replace legacy idioms with modern Java features; Adopt Java 8+ language features safely. Part of Plinth Toolkit
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/jabrena/plinth --skill 141-java-refactoring-with-modern-features- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads 141-java-refactoring-with-modern-features automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Modern Java Development Guidelines (Java 8+)
Identify and apply modern Java (Java 8+) refactoring opportunities to improve readability, maintainability, and performance.
What is covered in this Skill?
- Lambda expressions and method references (over anonymous classes)
- Stream API for declarative collection processing
Optionalfor null-safe APIsjava.timeAPI (replacingDate/Calendar)- Default interface methods,
vartype inference - Unmodifiable collection factory methods (
List.of(),Set.of(),Map.of()) - Text blocks for multi-line strings
- Java 25 Flexible Constructor Bodies (JEP 513)
- Java 25 Module Import Declarations (JEP 511)
Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.
Constraints
Before applying any modern Java refactoring, ensure the project compiles. If compilation fails, stop immediately — do not proceed until the project compiles successfully. After applying improvements, run full verification.
- MANDATORY: Run
./mvnw compileormvn compilebefore applying any changes - SAFETY: If compilation fails, stop immediately — do not proceed until the project compiles successfully
- VERIFY: Run
./mvnw clean verifyormvn clean verifyafter applying improvements - BEFORE APPLYING: Read the reference for detailed good/bad examples, constraints, and safeguards for each modern Java feature
- EDGE CASE: If request scope is ambiguous, stop and ask a clarifying question before applying changes
- EDGE CASE: If required inputs, files, or tooling are missing, report what is missing and ask whether to proceed with setup guidance
When to use this skill
- Review Java code for modern Java development
- Apply best practices for modern Java development in Java code
- Modernize Java code with records pattern matching or switch expressions
- Replace legacy idioms with modern Java features
- Adopt Java 8+ language features safely
Workflow
- Compile project before modernization
Run ./mvnw compile or mvn compile and stop immediately if compilation fails.
- Read modern-Java reference and identify candidates
Read references/141-java-refactoring-with-modern-features.md and identify high-value opportunities to adopt modern Java features.
- Apply modern Java refactorings
Refactor incrementally using appropriate language/library features while preserving behavior and readability.
- Verify with full build
Run ./mvnw clean verify or mvn clean verify after applying improvements.
Reference
For detailed guidance, examples, and constraints, see references/141-java-refactoring-with-modern-features.md.
FAQ
What does the 141-java-refactoring-with-modern-features skill do?
Use when you need to refactor Java code to adopt modern Java features (Java 8+) — including migrating anonymous classes to lambdas, replacing Iterator loops with Stream API, adopting Optional for null safety, switching from legacy Date/Calendar to java.time, using collection factory methods, applying text blocks, var inference, or leveraging Java 25 features like flexible constructor bodies and module import declarations. This should trigger for requests such as Review Java code for modern Java development; Apply best practices for modern Java development in Java code; Modernize Java code with records pattern matching or switch expressions; Replace legacy idioms with modern Java features; Adopt Java 8+ language features safely. Part of Plinth Toolkit
How do I install 141-java-refactoring-with-modern-features?
Run npx skills add https://github.com/jabrena/plinth --skill 141-java-refactoring-with-modern-features in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/141-java-refactoring-with-modern-features/ (personal) or .claude/skills/141-java-refactoring-with-modern-features/ (project).
Which AI agents can use 141-java-refactoring-with-modern-features?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is 141-java-refactoring-with-modern-features safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains 141-java-refactoring-with-modern-features?
It is published by jabrena in jabrena/plinth. It has 430 recorded installs.
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