checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
    "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
    "https://checkstyle.org/dtds/configuration_1_3.dtd">

<!--
    Custom Checkstyle configuration for FlossWare Commons.
    Based on Google Java Style with project-specific adjustments:
      - 150 character line length (relaxed from 100)
      - 4-space indentation with 4-space continuation
      - Relaxed Javadoc requirements (no @author required)
      - Import ordering: static, then java/javax, then third-party
      - Multiple empty lines allowed (existing code pattern)
-->
<module name="Checker">
    <property name="charset" value="UTF-8"/>
    <property name="severity" value="warning"/>
    <property name="fileExtensions" value="java"/>

    <!-- Exclude module-info.java from checks -->
    <module name="BeforeExecutionExclusionFileFilter">
        <property name="fileNamePattern" value="module\-info\.java$"/>
    </module>

    <!-- Suppression filters -->
    <module name="SuppressWarningsFilter"/>

    <!-- File-level checks -->
    <module name="FileTabCharacter">
        <property name="eachLine" value="true"/>
    </module>

    <module name="LineLength">
        <property name="fileExtensions" value="java"/>
        <property name="max" value="150"/>
        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
    </module>

    <module name="NewlineAtEndOfFile"/>

    <module name="TreeWalker">
        <!-- Enable @SuppressWarnings annotation support -->
        <module name="SuppressWarningsHolder"/>

        <!-- Import checks -->
        <module name="AvoidStarImport"/>
        <module name="RedundantImport"/>
        <module name="UnusedImports"/>
        <module name="CustomImportOrder">
            <property name="sortImportsInGroupAlphabetically" value="true"/>
            <property name="separateLineBetweenGroups" value="true"/>
            <property name="customImportOrderRules" value="STATIC###STANDARD_JAVA_PACKAGE###THIRD_PARTY_PACKAGE"/>
            <property name="tokens" value="IMPORT, STATIC_IMPORT, PACKAGE_DEF"/>
        </module>

        <!-- Naming conventions (Google style) -->
        <module name="PackageName">
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
        </module>
        <module name="TypeName"/>
        <module name="MemberName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="ParameterName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="LambdaParameterName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="CatchParameterName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="LocalVariableName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="ClassTypeParameterName">
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
        </module>
        <module name="MethodTypeParameterName">
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
        </module>
        <module name="InterfaceTypeParameterName">
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
        </module>
        <module name="MethodName">
            <property name="format" value="^[a-z][a-zA-Z0-9_]*$"/>
        </module>
        <module name="ConstantName"/>

        <!-- Whitespace checks -->
        <module name="GenericWhitespace"/>
        <module name="MethodParamPad"/>
        <module name="NoWhitespaceBefore"/>
        <module name="NoWhitespaceAfter"/>
        <module name="ParenPad"/>
        <module name="TypecastParenPad"/>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround">
            <property name="allowEmptyConstructors" value="true"/>
            <property name="allowEmptyMethods" value="true"/>
            <property name="allowEmptyTypes" value="true"/>
            <property name="allowEmptyLoops" value="true"/>
            <property name="allowEmptyLambdas" value="true"/>
            <property name="allowEmptyCatches" value="true"/>
        </module>
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
            <property name="allowMultipleEmptyLines" value="true"/>
            <property name="allowMultipleEmptyLinesInsideClassMembers" value="true"/>
        </module>
        <module name="OperatorWrap">
            <property name="option" value="NL"/>
            <property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR, METHOD_REF, TYPE_EXTENSION_AND"/>
        </module>
        <module name="SeparatorWrap">
            <property name="id" value="SeparatorWrapDot"/>
            <property name="tokens" value="DOT"/>
            <property name="option" value="nl"/>
        </module>
        <module name="SeparatorWrap">
            <property name="id" value="SeparatorWrapComma"/>
            <property name="tokens" value="COMMA"/>
            <property name="option" value="EOL"/>
        </module>

        <!-- Block checks -->
        <module name="AvoidNestedBlocks"/>
        <module name="EmptyBlock">
            <property name="option" value="TEXT"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
        </module>
        <module name="EmptyCatchBlock">
            <property name="exceptionVariableName" value="expected|ignore"/>
        </module>
        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly">
            <property name="id" value="RightCurlySame"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_DO"/>
        </module>
        <module name="RightCurly">
            <property name="id" value="RightCurlyAlone"/>
            <property name="option" value="alone"/>
            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT, ANNOTATION_DEF, ENUM_DEF, INTERFACE_DEF, RECORD_DEF, COMPACT_CTOR_DEF"/>
        </module>

        <!-- Coding checks -->
        <module name="FallThrough"/>
        <module name="MissingSwitchDefault"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="NoFinalizer"/>
        <module name="OneStatementPerLine"/>
        <module name="OneTopLevelClass"/>
        <module name="OverloadMethodsDeclarationOrder"/>
        <module name="VariableDeclarationUsageDistance"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>
        <module name="StringLiteralEquality"/>
        <module name="UnnecessarySemicolonAfterOuterTypeDeclaration"/>
        <module name="UnnecessarySemicolonAfterTypeMemberDeclaration"/>
        <module name="UnnecessarySemicolonInEnumeration"/>
        <module name="UnnecessarySemicolonInTryWithResources"/>

        <!-- Annotation checks -->
        <module name="AnnotationLocation">
            <property name="id" value="AnnotationLocationMostCases"/>
            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, RECORD_DEF, COMPACT_CTOR_DEF"/>
        </module>
        <module name="AnnotationLocation">
            <property name="id" value="AnnotationLocationVariables"/>
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="allowSamelineMultipleAnnotations" value="true"/>
        </module>

        <!-- Javadoc checks (relaxed: no @author required, missing Javadoc allowed) -->
        <module name="InvalidJavadocPosition"/>
        <module name="JavadocMethod">
            <property name="accessModifiers" value="public"/>
            <property name="allowMissingParamTags" value="true"/>
            <property name="allowMissingReturnTag" value="true"/>
        </module>
        <module name="JavadocType">
            <property name="authorFormat" value=""/>
            <property name="allowUnknownTags" value="true"/>
        </module>
        <module name="JavadocStyle">
            <property name="checkFirstSentence" value="false"/>
        </module>
        <module name="NonEmptyAtclauseDescription"/>
        <module name="AtclauseOrder">
            <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
        </module>

        <!-- Modifier checks -->
        <module name="ModifierOrder"/>
        <module name="RedundantModifier"/>

        <!-- Miscellaneous checks -->
        <module name="ArrayTypeStyle"/>
        <module name="CommentsIndentation"/>
        <module name="Indentation">
            <property name="basicOffset" value="4"/>
            <property name="braceAdjustment" value="0"/>
            <property name="caseIndent" value="4"/>
            <property name="throwsIndent" value="4"/>
            <property name="lineWrappingIndentation" value="4"/>
            <property name="arrayInitIndent" value="4"/>
        </module>
        <module name="OuterTypeFilename"/>
        <module name="UpperEll"/>
    </module>
</module>