| 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).
