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">
    <module name="FileTabCharacter"/>
    <module name="LineLength">
        <property name="max" value="120"/>
    </module>
    <module name="RegexpSingleline">
        <property name="format" value="\s+$"/>
        <property name="message" value="Line has trailing whitespace."/>
    </module>
    <module name="RegexpMultiline">
        <property name="matchAcrossLines" value="true"/>
        <property name="format" value="\A[\r]?\n"/>
        <property name="message" value="File must not start with an empty line."/>
    </module>
    <module name="RegexpMultiline">
        <property name="matchAcrossLines" value="true"/>
        <property name="format" value="[\r]?\n[\r]?\n\z"/>
        <property name="message" value="File must not end with an empty line."/>
    </module>
    <module name="RegexpMultiline">
        <property name="matchAcrossLines" value="true"/>
        <property name="format" value="\n[ \t]*\n[ \t]*\n"/>
        <property name="message" value="Double empty lines are not allowed."/>
    </module>
    <module name="TreeWalker">
                <module name="ImportOrder">
                    <property name="ordered" value="true"/>
                    <property name="separated" value="true"/>
                    <property name="groups" value="java,javax,org,com"/>
                    <property name="option" value="top"/>
                </module>
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
        </module>
        <module name="AvoidStarImport"/>
        <module name="Indentation">
            <property name="basicOffset" value="4"/>
            <property name="tabWidth" value="4"/>
        </module>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround"/>
        <module name="NoWhitespaceBefore"/>
        <module name="NoWhitespaceAfter"/>
        <module name="NeedBraces"/>
        <module name="LeftCurly"/>
        <module name="RightCurly"/>
        <module name="MethodParamPad"/>
        <module name="ParenPad"/>
        <module name="TypeName"/>
        <module name="MethodName"/>
        <module name="ParameterName"/>
        <module name="LocalVariableName"/>
        <module name="MemberName"/>
        <module name="VariableDeclarationUsageDistance"/>
        <module name="FinalLocalVariable"/>
        <module name="RedundantModifier"/>
        <module name="RedundantImport"/>
        <module name="UnusedImports"/>
        <module name="JavadocMethod">
            <property name="allowMissingParamTags" value="false"/>
            <property name="allowMissingReturnTag" value="false"/>
            <property name="validateThrows" value="true"/>
            <property name="accessModifiers" value="public,protected,package,private"/>
        </module>
        <module name="JavadocType">
            <property name="authorFormat" value=".+"/>
            <property name="versionFormat" value=".+"/>
        </module>
        <module name="JavadocVariable"/>
        <module name="SummaryJavadoc">
            <property name="forbiddenSummaryFragments"
                value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
        </module>
        <module name="CyclomaticComplexity">
            <property name="max" value="10"/>
        </module>
        <module name="MethodLength">
            <property name="max" value="60"/>
        </module>
        <module name="ClassFanOutComplexity">
            <property name="max" value="20"/>
        </module>
        <module name="MagicNumber">
            <property name="ignoreNumbers" value="-1, 0, 1, 2"/>
            <property name="ignoreAnnotation" value="true"/>
            <property name="ignoreFieldDeclaration" value="true"/>
        </module>
    </module>
</module>