checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC
        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
        "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">

    <property name="severity" value="warning"/>
    <property name="fileExtensions" value="java"/>

    <!-- ─── Exclusions ─────────────────────────────────────────────────────── -->
    <!-- module-info.java uses Java 9 module syntax not supported by the       -->
    <!-- bundled Checkstyle parser. It contains no style-relevant content.     -->

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

    <!-- ─── File-level checks ──────────────────────────────────────────────── -->

    <module name="FileTabCharacter"/>
    <module name="NewlineAtEndOfFile"/>
    <module name="LineLength">
        <property name="max" value="120"/>
    </module>

    <!-- ─── Tree walker (per-file checks) ─────────────────────────────────── -->

    <module name="TreeWalker">

        <!-- Imports -->
        <module name="AvoidStarImport"/>
        <module name="RedundantImport"/>
        <module name="UnusedImports"/>

        <!-- Naming -->
        <module name="TypeName"/>
        <module name="MethodName"/>
        <module name="ConstantName"/>
        <module name="MemberName"/>
        <module name="ParameterName"/>

        <!-- Javadoc -->
        <module name="JavadocMethod">
            <property name="accessModifiers" value="public"/>
        </module>
        <module name="JavadocType">
            <property name="scope" value="public"/>
        </module>
        <module name="JavadocVariable">
            <property name="scope" value="public"/>
        </module>

        <!-- Braces -->
        <module name="NeedBraces"/>
        <module name="LeftCurly"/>
        <module name="RightCurly"/>

        <!-- Whitespace -->
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround"/>
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
        </module>

        <!-- Indentation -->
        <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>

        <!-- Coding -->
        <module name="MissingSwitchDefault"/>
        <module name="FallThrough"/>
        <module name="OneStatementPerLine"/>
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>

        <!-- Class design -->
        <module name="HideUtilityClassConstructor"/>

        <!-- Miscellaneous -->
        <module name="UpperEll"/>
        <module name="ArrayTypeStyle"/>
        <module name="OuterTypeFilename"/>

    </module>

</module>