java-conventions

name	java-conventions
description	Java coding conventions — naming, records, Optional, streams, logging, and dependency injection
compatibility	>=1.4

Java Conventions

Skill metadata: version "1.0"; license MIT; tags [java, conventions, records, streams, spring-boot]; recommended tools [codebase, editFiles].

When to use

• Writing or reviewing Java source files
• Enforcing modern Java idioms and patterns

File scope

Applies to: **/*.java

Conventions

• Target the latest LTS Java version (21+). Use records, sealed classes, pattern matching where applicable.
• Use PascalCase for classes and interfaces, camelCase for methods and variables, SCREAMING_SNAKE_CASE for constants.
• Use record types for immutable value objects instead of mutable POJOs with getters/setters.
• Use Optional<T> as a return type for methods that may not produce a result. Never use Optional as a field or parameter type.
• Prefer var for local variables when the type is obvious from the right-hand side.
• Use Stream API for collection transformations — avoid manual loops for filter/map/reduce operations.
• Use try-with-resources for all AutoCloseable objects (I/O, database connections, HTTP clients).
• Use SLF4J with parameterized messages for logging: log.info("User {} logged in", userId). Never concatenate log messages.
• Prefer constructor injection over field injection for dependency injection frameworks.
• Use final on classes, methods, and parameters where mutability is not needed.
• Follow the Effective Java guidelines: minimize mutability, prefer composition over inheritance, design for extension or prohibit it.
• Pin dependency versions explicitly in the build file. Use dependency management BOMs for version alignment.