111-java-object-oriented-design

Guidelines for designing and refactoring object-oriented Java software, where programs are organized around interacting classes and objects.

In plain words
What is it for?
Use them when creating or reviewing Java classes, choosing composition or inheritance, applying SOLID principles, or refactoring code smells.
Why use it?
They help prevent tightly coupled, difficult-to-change code by covering class design, interfaces, immutability, and common design problems.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/alkoleft/platform-context-exporter/111-java-object-oriented-design
Clone the repo
git clone --depth 1 https://github.com/alkoleft/platform-context-exporter

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 17,774 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.17774
Opus 5 $0.00000 $0.08887
Sonnet 5 $0.00000 $0.03555
Haiku 4.5 $0.00000 $0.01777

Measured yesterday against content hash 1f8d1388411e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

111-java-object-oriented-design scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/111-java-object-oriented-design.mdc · 2,418 lines

How it starts

The opening of the file, as written. The whole thing — 2,418 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Java Object-Oriented Design Guidelines

This document provides comprehensive guidelines for robust Java object-oriented design and refactoring. It emphasizes core principles like SOLID, DRY, and YAGNI, best practices for class and interface design including favoring composition over inheritance and designing for immutability. The rules also cover mastering encapsulation, inheritance, and polymorphism, and finally, identifying and refactoring common object-oriented design code smells such as God Classes, Feature Envy, and Data Clumps to promote maintainable, flexible, and understandable code.

Implementing These Principles

These guidelines are built upon the following core principles:

  1. Adherence to Fundamental Design Principles: Embrace foundational principles like SOLID, DRY, and YAGNI. These principles are key to building systems that are robust, maintainable, flexible, and easy to understand.
  2. Effective Class and Interface Design: Employ best practices for designing classes and interfaces. This includes favoring composition over inheritance to achieve flexibility, programming to an interface rather than an implementation to promote loose coupling, keeping classes small and focused on a single responsibility, and designing for immutability where appropriate to enhance simplicity and thread-safety.
  3. Mastery of Core OOP Concepts: Thoroughly understand and correctly apply the pillars of object-oriented programming:
    • Encapsulation: Protect internal state and expose behavior through well-defined interfaces.
    • Inheritance: Model true "is-a" relationships, ensuring subclasses are substitutable for their base types (Liskov Substitution Principle).
    • Polymorphism: Allow objects of different types to respond to the same message in their own way, simplifying client code.
  4. Proactive Code Smell Management: Develop the ability to identify common object-oriented design "code smells" (e.g., God Class, Feature Envy, Data Clumps, Refused Bequest). Recognizing and refactoring these smells is crucial for improving the long-term health, maintainability, and clarity of the codebase.

Read the full file on GitHub · 2,418 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 2,418 lines · 17,774 tokens per session scan A 1f8d1388411e

Subscribe to this mod's changes

111-java-object-oriented-design is a cursor rule published in the GitHub repository alkoleft/platform-context-exporter (48 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 17,774 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.