# 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 m…

- **Type:** Skill
- **Install:** `agentstack add skill-jabrena-cursor-rules-java-141-java-refactoring-with-modern-features`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [jabrena](https://agentstack.voostack.com/s/jabrena)
- **Installs:** 0
- **Category:** [Developer Tools](https://agentstack.voostack.com/c/developer-tools)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [jabrena](https://github.com/jabrena)
- **Source:** https://github.com/jabrena/cursor-rules-java/tree/main/skills/141-java-refactoring-with-modern-features
- **Website:** https://jabrena.github.io/cursor-rules-java/

## Install

```sh
agentstack add skill-jabrena-cursor-rules-java-141-java-refactoring-with-modern-features
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# 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 APIs
- `java.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
- **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

## Workflow

1. **Compile project before modernization**

Run `./mvnw compile` or `mvn compile` and stop immediately if compilation fails.

2. **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.

3. **Apply modern Java refactorings**

Refactor incrementally using appropriate language/library features while preserving behavior and readability.

4. **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](references/141-java-refactoring-with-modern-features.md).

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [jabrena](https://github.com/jabrena)
- **Source:** [jabrena/cursor-rules-java](https://github.com/jabrena/cursor-rules-java)
- **License:** Apache-2.0
- **Homepage:** https://jabrena.github.io/cursor-rules-java/

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-jabrena-cursor-rules-java-141-java-refactoring-with-modern-features
- Seller: https://agentstack.voostack.com/s/jabrena
- Browse the marketplace: https://agentstack.voostack.com/browse

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