checkstyle-rules

Rules for checkstyle. Share rules among projects.

Overview

The rules are based on the default Sun checks, with some modifications.

Usage

You can configure the maven-checkstyle-plugin in this way:

<build>
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-checkstyle-plugin</artifactId>
    <version>3.1.2</version>
    <executions>
      <execution>
        <id>validate</id>
        <phase>validate</phase>
        <goals>
          <goal>check</goal>
        </goals>
      </execution>
    </executions>
    <dependencies>
      <dependency>
        <groupId>com.puppycrawl.tools</groupId>
        <artifactId>checkstyle</artifactId>
        <version>8.45.1</version>
      </dependency>
      <dependency>
        <groupId>com.github.ngeor</groupId>
        <artifactId>checkstyle-rules</artifactId>
        <version>4.9.3</version>
      </dependency>
    </dependencies>
    <configuration>
      <configLocation>com/github/ngeor/checkstyle.xml</configLocation>
      <includeTestSourceDirectory>true</includeTestSourceDirectory>
    </configuration>
  </plugin>
</build>

Rules in details

Annotations

Rule	Status
AnnotationLocation	Not Used
AnnotationOnSameLine	Not Used
AnnotationUseStyle	Not Used
MissingDeprecated	Not Used
MissingOverride	Not Used
PackageAnnotation	Not Used
SuppressWarnings	Not Used
SuppressWarningsHolder	Used

Block Checks

Rule	Status
AvoidNestedBlocks	Used
EmptyBlock	Used
EmptyCatchBlock	Not Used
LeftCurly	Used
NeedBraces	Used
RightCurly	Used

Class Design

Rule	Status
DesignForExtension	Disabled
FinalClass	Used
HideUtilityClassConstructor	Used
InnerTypeLast	Not Used
InterfaceIsType	Used
MutableException	Not Used
OneTopLevelClass	Enabled
ThrowsCount	Not Used
VisibilityModifier	Used

Coding

Rule	Status
ArrayTrailingComma	Not Used
AvoidInlineConditionals	Disabled
CovariantEquals	Enabled
DeclarationOrder	Enabled
DefaultComesLast	Enabled
EmptyStatement	Used
EqualsAvoidNull	Enabled
EqualsHashCode	Used
ExplicitInitialization	Enabled
FallThrough	Enabled
FinalLocalVariable	Not Used
HiddenField	Altered
IllegalCatch	Enabled
IllegalInstantiation	Used
IllegalThrows	Enabled
IllegalToken	Not Used
IllegalTokenText	Not Used
IllegalType	Enabled
InnerAssignment	Used
MagicNumber	Altered
MissingCtor	Not Used
MissingSwitchDefault	Used
ModifiedControlVariable	Enabled
MultipleStringLiterals	Not Used
MultipleVariableDeclarations	Enabled
NestedForDepth	Enabled
NestedIfDepth	Enabled
NestedTryDepth	Enabled
NoClone	Enabled
NoFinalizer	Enabled
OneStatementPerLine	Enabled
OverloadMethodsDeclarationOrder	Enabled
PackageDeclaration	Enabled
ParameterAssignment	Enabled
RequireThis	Not Used
ReturnCount	Not Used
SimplifyBooleanExpression	Used
SimplifyBooleanReturn	Used
StringLiteralEquality	Enabled
SuperClone	Not Used
SuperFinalize	Not Used
UnnecessaryParentheses	Enabled
UnnecessarySemicolonAfterTypeMemberDeclaration	Not Used
UnnecessarySemicolonInEnumeration	Not Used
UnnecessarySemicolonInTryWithResources	Not Used
VariableDeclarationUsageDistance	Not Used

HiddenField

• ignoreConstructorParameter set to true
• ignoreSetter set to true

MagicNumber

Allows magic numbers in hash code, field declarations and annotations.

Headers

Rule	Status
Header	Disabled
RegexpHeader	Not Used

Imports

Rule	Status
AvoidStarImport	Not Used
AvoidStaticImport	Not Used
CustomImportOrder	Not Used
IllegalImport	Used
ImportControl	Not Used
ImportOrder	Altered
RedundantImport	Used
UnusedImports	Used

ImportOrder

Matches Palantir style:

• All static imports in one group, alphabetically sorted
• One line separator
• All non-static imports in one group, alphabetically sorted

Javadoc Comments

Rule	Status
AtclauseOrder	Not Used
InvalidJavadocPosition	Not Used
JavadocBlockTagLocation	Not Used
JavadocMethod	Not Used
JavadocPackage	Not Used
JavadocParagraph	Not Used
JavadocStyle	Used
JavadocTagContinuationIndentation	Not Used
JavadocType	Not Used
JavadocVariable	Not Used
MissingJavadocMethod	Not Used
MissingJavadocPackage	Not Used
MissingJavadocType	Not Used
NonEmptyAtclauseDescription	Not Used
SingleLineJavadoc	Not Used
SummaryJavadoc	Not Used
WriteTag	Not Used

Metrics

Rule	Status
BooleanExpressionComplexity	Not Used
ClassDataAbstractionCoupling	Not Used
ClassFanOutComplexity	Not Used
CyclomaticComplexity	Not Used
JavaNCSS	Not Used
NPathComplexity	Not Used

Miscellaneous

Rule	Status
ArrayTypeStyle	Used
AvoidEscapedUnicodeCharacters	Not Used
CommentsIndentation	Enabled
DescendantToken	Not Used
FinalParameters	Disabled
Indentation	Enabled
NewlineAtEndOfFile	Used
OrderedProperties	Not Used
OuterTypeFilename	Enabled
TodoComment	Disabled
TrailingComment	Not Used
Translation	Used
UncommentedMain	Not Used
UniqueProperties	Not Used
UpperEll	Used

Modifiers

Rule	Status
ClassMemberImpliedModifier	Not Used
InterfaceMemberImpliedModifier	Not Used
ModifierOrder	Used
RedundantModifier	Used

Naming Conventions

Rule	Status
AbbreviationAsWordInName	Not Used
AbstractClassName	Not Used
CatchParameterName	Not Used
ClassTypeParameterName	Not Used
ConstantName	Used
InterfaceTypeParameterName	Not Used
LambdaParameterName	Not Used
LocalFinalVariableName	Used
LocalVariableName	Used
MemberName	Used
MethodName	Altered
MethodTypeParameterName	Not Used
PackageName	Altered
ParameterName	Used
StaticVariableName	Used
TypeName	Used

MethodName

Using Google flavor to permit underscore in test method names: ^[a-z][a-z0-9][a-zA-Z0-9_]*$"

PackageName

Limited to lowercase letters and numbers: ^[a-z]+(\.[a-z][a-z0-9]*)*$

Regexp

Rule	Status
Regexp	Not Used
RegexpMultiline	Not Used
RegexpOnFilename	Not Used
RegexpSingleline	Altered
RegexpSinglelineJava	Not Used

RegexSingleline

Verifies that lines do not have trailing spaces.

Size Violations

Rule	Status
AnonInnerLength	Not Used
ExecutableStatementCount	Not Used
FileLength	Used
LineLength	Altered increased to 120 characters
MethodCount	Not Used
MethodLength	Used
OuterTypeNumber	Not Used
ParameterNumber	Used

Whitespace

Rule	Status
EmptyForInitializerPad	Not Used
EmptyForIteratorPad	Used
EmptyLineSeparator	Altered
FileTabCharacter	Used
GenericWhitespace	Used
MethodParamPad	Used
NoLineWrap	Not Used
NoWhitespaceAfter	Used
NoWhitespaceBefore	Used
OperatorWrap	Used
ParenPad	Used
SeparatorWrap	Not Used
SingleSpaceSeparator	Not Used
TypecastParenPad	Used
WhitespaceAfter	Used
WhitespaceAround	Altered

EmptyLineSeparator

• allowNoEmptyLineBetweenFields set to true
• allowMultipleEmptyLines set to false

WhitespaceAround

• allows empty constructor bodies
• allows empty methods
• allows empty class, interface and enum bodies

Suppressions

It is possible to specify an XML file with suppressions. The file is optional and it needs to be in checkstyle/suppressions.xml.

Example file to ignore magic numbers and multiple string literals in unit tests:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suppressions PUBLIC
    "-//Puppy Crawl//DTD Suppressions 1.0//EN"
    "http://checkstyle.sourceforge.net/dtds/suppressions_1_0.dtd">
<suppressions>
    <suppress files="Test.java$" checks="MagicNumber" />
    <suppress files="Test.java$" checks="MultipleStringLiterals" />
</suppressions>

It is also possible to suppress violations using the @SuppressWarnings annotation.