141-java-refactoring-with-modern-features - Claude MCP Skill

# Modern Java Development Guidelines (Java 8+)

Identify and apply modern Java (Java 8+) refactoring opportunities to improve readability, maintainability, and performance.

**Prerequisites:** Run `./mvnw compile` or `mvn compile` before applying any changes. If compilation fails, **stop immediately** — do not proceed until the project compiles successfully.

**Core areas:** Lambda expressions and method references (over anonymous classes), Stream API for declarative collection processing, `Optional` for null-safe APIs, `java.time` API (replacing `Date`/`Calendar`), default interface methods, `var` type inference, unmodifiable collection factory methods (`List.of()`, `Set.of()`, `Map.of()`), `CompletableFuture` for composable async programming, text blocks for multi-line strings, Java 25 Flexible Constructor Bodies (JEP 513), and Java 25 Module Import Declarations (JEP 511).

**Scope:** The reference is organized by examples (with good/bad code patterns) for each core area. Apply recommendations based on applicable examples; validate compilation before changes and run `./mvnw clean verify` or `mvn clean verify` after applying improvements.

**Before applying changes:** Read the reference for detailed good/bad examples, constraints, and safeguards for each modern Java feature.

## Reference

For detailed guidance, examples, and constraints, see [references/141-java-refactoring-with-modern-features.md](references/141-java-refactoring-with-modern-features.md).