checkstyle.xml

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

<module name="Checker">
    <module name="TreeWalker">
        <module name="AvoidStarImport"/>
        <module name="AvoidStaticImport"/>
        <module name="ConstantName"/>
        <module name="DeclarationOrder"/>
        <module name="EqualsHashCode"/>
        <module name="FallThrough"/>
        <module name="FinalLocalVariable"/>
        <module name="FinalParameters"/>
        <module name="Regexp">
            <property name="format" value="[ \t]+$"/>
            <property name="illegalPattern" value="true"/>
            <property name="message" value="Trailing whitespace"/>
        </module>
        <module name="Regexp">
            <property name="format" value="System\.out\.println"/>
            <property name="illegalPattern" value="true"/>
            <property name="ignoreComments" value="true"/>
        </module>
        <module name="HiddenField">
            <property name="ignoreConstructorParameter" value="true"/>
            <property name="ignoreSetter" value="true"/>
        </module>
        <module name="HideUtilityClassConstructor"/>
        <module name="IllegalCatch"/>
        <module name="IllegalImport"/>
        <module name="Indentation">
            <property name="basicOffset" value="4"/>
            <property name="caseIndent"  value="4"/>
        </module>
        <module name="JavadocMethod">
            <property name="validateThrows" value="false"/>
        </module>
        <module name="JavadocStyle"/>
        <module name="JavadocVariable"/>
        <module name="MissingSwitchDefault"/>
        <module name="ModifierOrder"/>
        <module name="MultipleStringLiterals">
            <property name="ignoreStringsRegexp" value='^(("")|(".")|("\\\\"))$'/>
        </module>
        <module name="MultipleVariableDeclarations"/>
        <module name="NoWhitespaceAfter">
            <property name="tokens"
                      value="AT, INC, DEC, UNARY_MINUS, UNARY_PLUS, BNOT, LNOT, DOT,
                             ARRAY_DECLARATOR, INDEX_OP"/>
        </module>
        <module name="NoWhitespaceBefore"/>
        <module name="OperatorWrap">
            <property name="option" value="eol"/>
        </module>
        <module name="RedundantModifier"/>
        <module name="StringLiteralEquality"/>
        <module name="TodoComment">
            <property name="severity" value="warning"/>
        </module>
        <module name="UnnecessaryParentheses">
            <property name="tokens"
                      value="EXPR, IDENT, NUM_DOUBLE, NUM_FLOAT, NUM_INT, NUM_LONG, STRING_LITERAL,
                             LITERAL_NULL, LITERAL_FALSE, LITERAL_TRUE, ASSIGN, BAND_ASSIGN, BOR_ASSIGN,
                             BSR_ASSIGN, BXOR_ASSIGN, DIV_ASSIGN, MINUS_ASSIGN, MOD_ASSIGN, PLUS_ASSIGN,
                             SL_ASSIGN, SR_ASSIGN, STAR_ASSIGN, LAMBDA, TEXT_BLOCK_LITERAL_BEGIN, LAND,
                             LOR, LITERAL_INSTANCEOF, GT, LT, GE, LE, EQUAL, NOT_EQUAL, UNARY_MINUS,
                             UNARY_PLUS, INC, DEC, LNOT, BNOT, POST_INC, POST_DEC"/>
        </module>
        <module name="NeedBraces"/>
        <module name="UnusedImports"/>
        <module name="VisibilityModifier"/>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround">
            <property name="tokens"
                      value="ASSIGN, ARRAY_INIT, BAND, BAND_ASSIGN, BOR, BOR_ASSIGN, BSR, BSR_ASSIGN,
                             BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN, EQUAL, GE, GT,
                             LAND, LCURLY, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE,
                             LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN,
                             LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT,
                             MINUS, MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS,
                             PLUS_ASSIGN, QUESTION, RCURLY, SL, SLIST, SL_ASSIGN, SR,
                             SR_ASSIGN, STAR, STAR_ASSIGN"/>
        </module>
		<!-- Avoid Python keywords in method, class, interface and enum names -->
        <module name="IllegalIdentifierName">
            <property name="format"
                      value="(?i)^(?!(del|elif|except|from|global|in|is|lambda|nonlocal|not|or|pass|raise|with|yield)$).+$"/>
            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, METHOD_DEF, ENUM_DEF"/>
            <message key="name.invalidPattern" value="Name ''{0}'' is not allowed."/>
        </module>
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE\: stop ConstantName"/>
            <property name="onCommentFormat"  value="CHECKSTYLE\: resume ConstantName"/>
            <property name="checkFormat"      value="ConstantName"/>
        </module>
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE\: stop JavadocVariable check"/>
            <property name="onCommentFormat"  value="CHECKSTYLE\: resume JavadocVariable check"/>
            <property name="checkFormat"      value="JavadocVariable"/>
        </module>
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE\: stop VisibilityModifier check"/>
            <property name="onCommentFormat"  value="CHECKSTYLE\: resume VisibilityModifier check"/>
            <property name="checkFormat"      value="VisibilityModifierCheck"/>
        </module>
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE\: stop NoWhitespaceAfter check"/>
            <property name="onCommentFormat"  value="CHECKSTYLE\: resume NoWhitespaceAfter check"/>
            <property name="checkFormat"      value="NoWhitespaceAfter"/>
        </module>
        <module name="SuppressionCommentFilter">
          <property name="offCommentFormat" value="CHECKSTYLE\: stop Indentation check"/>
          <property name="onCommentFormat" value="CHECKSTYLE\: resume Indentation check"/>
          <property name="checkFormat" value="IndentationCheck"/>
        </module>
        <module name="SuppressionCommentFilter">
          <property name="offCommentFormat" value="CHECKSTYLE\: stop MultipleStringLiterals check"/>
          <property name="onCommentFormat" value="CHECKSTYLE\: resume MultipleStringLiterals check"/>
          <property name="checkFormat" value="MultipleStringLiteralsCheck"/>
        </module>
        <module name="SuppressionCommentFilter">
          <property name="offCommentFormat" value="CHECKSTYLE\: stop IllegalCatch check"/>
          <property name="onCommentFormat" value="CHECKSTYLE\: resume IllegalCatch check"/>
          <property name="checkFormat" value="IllegalCatchCheck"/>
        </module>
    </module>
    <module name="RegexpHeader">
      <property name="headerFile" value="${checkstyle.header.file}" />
      <property name="fileExtensions" value="java" />
    </module>
    <module name="FileTabCharacter"/>
    <module name="NewlineAtEndOfFile">
      <property name="lineSeparator" value="LF_CR_CRLF"/>
    </module>
</module>