codestyle

name	codestyle
description	Coding standards, formatting, and static-analysis conventions for Maven/Java projects using spring-javaformat, Checkstyle, and PMD. Use when checking or fixing code-style violations, or when asking what the project's formatting and naming rules are.

Maven/Java Coding Standards

Try it: /maven-quality:codestyle — or say "fix the code-style violations in this module".

These are sensible defaults for a Maven/Java project that uses spring-javaformat, Checkstyle, and PMD. Adjust thresholds, plugin versions, and module/path names to match your project.

Tooling (common case)

• Formatter: io.spring.javaformat:spring-javaformat-maven-plugin (tab indentation) — run spring-javaformat:apply before committing.
• Checkstyle: maven-checkstyle-plugin with io.spring.javaformat:spring-javaformat-checkstyle (SpringChecks) plus custom suppressions.
• PMD: maven-pmd-plugin with a custom ruleset.
• Config files (project root by default): checkstyle-suppressions.xml, pmd-ruleset.xml. Adjust paths if your project keeps them elsewhere.
• Violations typically fail the build at the validate phase. Adjust the bound phase if your pom.xml differs.

Formatting rules enforced by spring-javaformat

• Indentation: Tabs.
• Braces required: All if, else, for, while, do use {} even for single-line bodies.
• Lambda parentheses: Single-parameter lambdas have parentheses: (x) -> not x ->.
• Lambda blocks: Prefer expression body: (x) -> x.toString() not (x) -> { return x.toString(); }.
• Catch variables: Use ex not single-letter e: catch (Exception ex).
• Ternary parentheses: Wrap the condition: (a != null) ? a : b.
• No star imports: Explicit imports only, never import java.util.*.
• Newline at EOF: Files end with a trailing newline.

Common Checkstyle suppressions

Default suppressions kept in checkstyle-suppressions.xml. Add or remove to taste:

• SpringHeaderCheck — no license header requirement.
• JavadocPackage, JavadocType, JavadocMethod, JavadocVariable, MissingJavadocType, MissingJavadocMethod, SpringJavadoc — Javadoc not enforced.
• RegexpSinglelineJava — no per-line regex restrictions.
• SpringImportOrder — import ordering not enforced.
• RequireThis — this. prefix not required.
• SpringTestFileName — flexible test file naming.

Common PMD exclusions

Patterns considered acceptable, excluded in pmd-ruleset.xml. Tighten for stricter projects:

• Best Practices: GuardLogStatement, LiteralsFirstInComparisons, UnusedAssignment, DoubleBraceInitialization, NonExhaustiveSwitch, RedundantFieldInitializer
• Code Style: LocalVariableNamingConventions, PrematureDeclaration, ConfusingTernary, UseLocaleWithCaseConversions, UseExplicitTypes, FieldNamingConventions
• Design: CognitiveComplexity, NcssCount, SimplifyConditional, CollapsibleIfStatements, GodClass, DataClass, TooManyFields
• Error Prone: ReturnEmptyCollectionRatherThanNull, AvoidDuplicateLiterals, NullAssignment

Naming

• Classes: PascalCase
• Methods / variables: camelCase
• Constants: UPPER_SNAKE_CASE

Lombok (if used)

• @Getter/@Setter for fields
• @Data for POJOs/DTOs
• @Builder with .toBuilder() for immutable construction
• @Slf4j for logging
• @NoArgsConstructor, @AllArgsConstructor as needed

Testing

• JUnit 5 with Assertions.
• Use @ParameterizedTest to avoid duplication.
• JaCoCo enforces a minimum line-coverage gate (default 80% — see the jacoco skill; adjust per project).

Workflow: check and fix violations

1. Auto-format first — fixes most style issues automatically:

./mvnw spring-javaformat:apply

2. Check remaining violations:

./mvnw validate 2>&1 | grep -E "violations|ERROR.*\.java|PMD Failure"

3. Fix remaining violations manually:

Violation	Fix
SpringCatch	Rename catch (Exception e) to catch (Exception ex)
NeedBraces	Add { } to single-line if/for/while
SpringLambda parens	Wrap single lambda param: x -> becomes (x) ->
SpringLambda block	Convert x -> { return expr; } to x -> expr
SpringTernary	Wrap condition in parens: (cond) ? a : b
AvoidStarImport	Replace import pkg.* with specific imports
SpringHideUtilityClassConstructor	Add private constructor + final class
AnnotationUseStyle trailing comma	Remove , before }) in annotations
AppendCharacterWithChar	Use .append('x') not .append("x") for single chars
MissingOverride	Add @Override on interface/superclass implementations

4. Re-format and validate until clean:

./mvnw spring-javaformat:apply && ./mvnw validate

Notes on invocation

• Examples use the Maven wrapper ./mvnw. If your environment has no wrapper, substitute your mvn binary (e.g. bash "/path/to/mvn" ...).
• For multi-module builds, scope checks with -pl <module> (e.g. the module that actually holds source and the quality plugins).