checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.2//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
<module name="Checker">
    <module name="NewlineAtEndOfFile" />

    <module name="FileLength" />

    <module name="FileTabCharacter">
        <property name="eachLine" value="true" />
    </module>

    <module name="RegexpSingleline">
        <property name="format" value="\s+$" />
        <property name="message" value="Line has trailing spaces." />
    </module>

    <module name="SuppressionFilter">
        <!-- note that $basedir must be set to TLD of heroic in your local dev
        environment for checkstyle to function. You may wish to emply the direnv
        utility to set this for you. -->
        <property name="file" value="${basedir}/suppressions.xml"/>
    </module>

    <property name="cacheFile" value="${basedir}/.cache/checkstyle-cache"/>

    <module name="LineLength">
        <property name="max" value="100"/>
    </module>

    <module name="SuppressWarningsFilter"/>

    <module name="TreeWalker">

        <module name="ArrayTypeStyle" />
        <module name="AvoidStarImport" />
        <module name="CommentsIndentation"/>
        <module name="EmptyForIteratorPad" />
        <!-- TODO uncomment this when someone's feeling brave enough to fix all the errors. -->
        <!--        <module name="EmptyLineSeparator">-->
        <!--            &lt;!&ndash; Do Not Allow multiple empty lines between class members. &ndash;&gt;-->
        <!--            <property name="allowMultipleEmptyLines" value="false"/>-->
        <!--            &lt;!&ndash; Do Not Allow multiple empty lines inside class members &ndash;&gt;-->
        <!--            <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>-->
        <!--            &lt;!&ndash;            &lt;!&ndash; Do Not enforce an empty line between fields. &ndash;&gt;&ndash;&gt;-->
        <!--            &lt;!&ndash;            <property name="allowNoEmptyLineBetweenFields" value="false"/>&ndash;&gt;-->
        <!--        </module>-->
        <module name="EmptyStatement" />
        <module name="EqualsHashCode" />
        <module name="IllegalImport" />
        <module name="IllegalInstantiation" />
        <!-- TODO uncomment this when someone's feeling brave enough to fix all the errors. -->
        <!-- Indentation. We go with the Checkstyle/Google default of 4 spaces. For details, see
        https://checkstyle.sourceforge.io/config_misc.html#Indentation_Properties .
        ... However, a lot (many, many files) of Heroic's java code is incorrectly indented with 2
        spaces unfortunately, which means the build fails. Hence commenting this out for now. -->
        <!-- <module name="Indentation"/>-->
        <module name="LeftCurly" />
        <module name="LocalFinalVariableName" />
        <module name="LocalVariableName" />
        <module name="MemberName" />
        <module name="MethodLength" />
        <module name="MethodName" />
        <module name="MethodParamPad" />
        <module name="MissingSwitchDefault" />
        <module name="ModifierOrder" />
        <module name="NeedBraces" />
        <module name="NoWhitespaceAfter" />
        <module name="NoWhitespaceBefore" />
        <module name="PackageName" />
        <module name="ParameterName" />
        <module name="ParenPad" />
        <module name="RedundantImport" />
        <module name="RightCurly" />
        <module name="SimplifyBooleanExpression" />
        <module name="StaticVariableName" />
        <module name="SuppressWarningsHolder"/>
        <module name="TypecastParenPad" />
        <module name="TypeName" />
        <module name="UnusedImports" />
        <module name="UpperEll" />
        <module name="WhitespaceAfter" />
        <module name="WhitespaceAround" />
    </module>

    <module name="Header">
        <property name="headerFile" value="${basedir}/tools/java.header"/>
        <property name="ignoreLines" value="2" />
        <property name="fileExtensions" value="java" />
    </module>
</module>