| name | 141-java-refactoring-with-modern-features |
| description | 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. Part of the skills-for-java project |
| license | Apache-2.0 |
| metadata | {"author":"Juan Antonio Breña Moral","version":"0.13.0-SNAPSHOT"} |
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
Optional for null-safe APIsjava.time API (replacing Date/Calendar)- Default interface methods,
var type 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 compile or mvn compile before applying any changes
- SAFETY: If compilation fails, stop immediately — do not proceed until the project compiles successfully
- VERIFY: Run
./mvnw clean verify or mvn clean verify after applying improvements
- BEFORE APPLYING: Read the reference for detailed good/bad examples, constraints, and safeguards for each modern Java feature
When to use this skill
- Review Java code for modern Java development
- Apply best practices for modern Java development in Java code
Reference
For detailed guidance, examples, and constraints, see references/141-java-refactoring-with-modern-features.md.
