checks.xml

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

<!--
    Checkstyle configuration that checks the Google coding conventions from Google Java Style
    that can be found at https://google.github.io/styleguide/javaguide.html

    Checkstyle is very configurable. Be sure to read the documentation at
    https://checkstyle.org (or in your downloaded distribution).

    To completely disable a check, just comment it out or delete it from the file.
    To suppress certain violations please review suppression filters.

    Authors: Max Vetrenko, Mauryan Kansara, Ruslan Diachenko, Roman Ivanov.
 -->

<module name="Checker">

  <property name="charset" value="UTF-8"/>

  <property name="severity" value="${org.checkstyle.google.severity}" default="warning"/>

  <property name="fileExtensions" value="java, properties, xml"/>
  <!-- Excludes all 'module-info.java' files             -->
  <!-- See https://checkstyle.org/filefilters/index.html -->
  <module name="BeforeExecutionExclusionFileFilter">
    <property name="fileNamePattern" value="module\-info\.java$"/>
  </module>

  <module name="SuppressWarningsFilter"/>

  <!-- https://checkstyle.org/filters/suppressionfilter.html -->
  <module name="SuppressionFilter">
    <property name="file" value="${org.checkstyle.google.suppressionfilter.config}"
           default="checkstyle-suppressions.xml" />
    <property name="optional" value="true"/>
  </module>

  <!-- https://checkstyle.org/filters/suppresswithnearbytextfilter.html -->
  <!--
  <module name="SuppressWithNearbyTextFilter">
    <property name="nearbyTextPattern"
              value="CHECKSTYLE.SUPPRESS\: (\w+) for ([+-]\d+) lines"/>
    <property name="checkPattern" value="$1"/>
    <property name="lineRange" value="$2"/>
  </module>
  -->

  <!-- Checks for whitespace                                   -->
  <!-- See https://checkstyle.org/checks/whitespace/index.html -->
  <module name="FileTabCharacter">
    <property name="eachLine" value="true"/>
  </module>

  <module name="LineLength">
    <property name="fileExtensions" value="java"/>
    <property name="max" value="100"/>
    <property name="ignorePattern"
             value="^package.*|^import.*|href\s*=\s*&quot;[^&quot;]*&quot;|http://|https://|ftp://|@Override"/>
  </module>

  <module name="TreeWalker">
    <module name="OuterTypeFilename"/>
    <module name="IllegalTokenText">
      <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
      <property name="format"
               value="\\u00(09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
      <property name="message"
               value="Consider using special escape sequence instead of octal value or Unicode escaped value."/>
    </module>
    <module name="AvoidEscapedUnicodeCharacters">
      <property name="allowEscapesForControlCharacters" value="true"/>
      <property name="allowByTailComment" value="true"/>
      <property name="allowNonPrintableEscapes" value="true"/>
    </module>
    <module name="AvoidStarImport">
      <property name="excludes" value="java.awt, javax.swing"/>
    </module>
    <!-- module name="OneTopLevelClass"/ -->
    <module name="NoLineWrap">
      <property name="tokens" value="PACKAGE_DEF, IMPORT, STATIC_IMPORT"/>
    </module>
    <module name="NeedBraces">
      <property name="tokens"
               value="LITERAL_DO, LITERAL_ELSE, LITERAL_FOR, LITERAL_IF, LITERAL_WHILE"/>
    </module>
    <module name="LeftCurly">
      <property name="tokens"
               value="ANNOTATION_DEF, CLASS_DEF, CTOR_DEF, ENUM_CONSTANT_DEF, ENUM_DEF,
                    INTERFACE_DEF, LAMBDA, LITERAL_CASE, LITERAL_CATCH, LITERAL_DEFAULT,
                    LITERAL_DO, LITERAL_ELSE, LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF,
                    LITERAL_SWITCH, LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, METHOD_DEF,
                    OBJBLOCK, STATIC_INIT, RECORD_DEF, COMPACT_CTOR_DEF"/>
    </module>
    <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>
    <module name="SuppressionXpathSingleFilter">
      <!-- suppression is required till https://github.com/checkstyle/checkstyle/issues/7541 -->
      <property name="id" value="RightCurlyAlone"/>
      <property name="query" value="//RCURLY[parent::SLIST[count(./*)=1]
                                     or preceding-sibling::*[last()][self::LCURLY]]"/>
    </module>
    <module name="WhitespaceAfter">
      <property name="tokens"
               value="COMMA, SEMI, TYPECAST, LITERAL_IF, LITERAL_ELSE,
                    LITERAL_WHILE, LITERAL_DO, LITERAL_FOR, DO_WHILE"/>
    </module>
    <module name="WhitespaceAround">
      <property name="allowEmptyConstructors" value="true"/>
      <property name="allowEmptyLambdas" value="true"/>
      <property name="allowEmptyMethods" value="true"/>
      <property name="allowEmptyTypes" value="true"/>
      <property name="allowEmptyLoops" value="true"/>
      <property name="ignoreEnhancedForColon" value="false"/>
      <property name="tokens"
               value="ASSIGN, BAND, BAND_ASSIGN, BOR, BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR,
                    BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN, DO_WHILE, EQUAL, GE, GT, LAMBDA, LAND,
                    LCURLY, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE, LITERAL_FINALLY,
                    LITERAL_FOR, LITERAL_IF, LITERAL_RETURN, LITERAL_SWITCH, 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, LITERAL_ASSERT, TYPE_EXTENSION_AND"/>
      <message key="ws.notFollowed"
              value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks
               may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
      <message key="ws.notPreceded"
              value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
    </module>
    <module name="SuppressionXpathSingleFilter">
      <property name="checks" value="WhitespaceAround"/>
      <property name="query" value="//*[self::LITERAL_IF or self::LITERAL_ELSE or self::STATIC_INIT
                                 or self::LITERAL_TRY or self::LITERAL_CATCH]/SLIST[count(./*)=1]
                                 | //*[self::STATIC_INIT or self::LITERAL_TRY or self::LITERAL_IF]
                                 //*[self::RCURLY][parent::SLIST[count(./*)=1]]"/>
    </module>
    <module name="RegexpSinglelineJava">
      <property name="format" value="\{[ ]+\}"/>
      <property name="message" value="Empty blocks should have no spaces. Empty blocks
                                   may only be represented as '{}' when not part of a
                                   multi-block statement (4.1.3)"/>
    </module>
    <module name="OneStatementPerLine"/>
    <module name="MultipleVariableDeclarations"/>
    <module name="ArrayTypeStyle"/>
    <module name="MissingSwitchDefault"/>
    <module name="FallThrough"/>
    <module name="UpperEll"/>
    <module name="ModifierOrder"/>
    <module name="DeclarationOrder"/>

    <!-- Coding -->
    <module name="CovariantEquals"/>
    <module name="DefaultComesLast"/>
    <module name="EmptyStatement"/>
    <module name="EqualsAvoidNull"/>
    <module name="EqualsHashCode"/>
    <module name="ExplicitInitialization"/>
    <module name="FallThrough"/>

    <module name="AvoidDoubleBraceInitialization"/>
    <module name="NoFinalizer"/>
    <module name="OneStatementPerLine"/>
    <module name="OverloadMethodsDeclarationOrder"/>
    <module name="PackageDeclaration"/>
    <module name="ParameterAssignment"/>
    <module name="RequireThis"/>
    <module name="SimplifyBooleanExpression"/>
    <module name="SimplifyBooleanReturn"/>
    <module name="StringLiteralEquality"/>
    <module name="SuperClone"/>
    <module name="SuperFinalize"/>

    <module name="EmptyLineSeparator">
      <property name="tokens"
               value="PACKAGE_DEF, IMPORT, STATIC_IMPORT, CLASS_DEF, INTERFACE_DEF, ENUM_DEF,
                    STATIC_INIT, INSTANCE_INIT, METHOD_DEF, CTOR_DEF, VARIABLE_DEF, RECORD_DEF,
                    COMPACT_CTOR_DEF"/>
      <property name="allowNoEmptyLineBetweenFields" value="true"/>
    </module>
    <module name="SingleSpaceSeparator" />
    <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>
    <module name="SeparatorWrap">
      <!-- ELLIPSIS is EOL until https://github.com/google/styleguide/issues/259 -->
      <property name="id" value="SeparatorWrapEllipsis"/>
      <property name="tokens" value="ELLIPSIS"/>
      <property name="option" value="EOL"/>
    </module>
    <module name="SeparatorWrap">
      <!-- ARRAY_DECLARATOR is EOL until https://github.com/google/styleguide/issues/258 -->
      <property name="id" value="SeparatorWrapArrayDeclarator"/>
      <property name="tokens" value="ARRAY_DECLARATOR"/>
      <property name="option" value="EOL"/>
    </module>
    <module name="SeparatorWrap">
      <property name="id" value="SeparatorWrapMethodRef"/>
      <property name="tokens" value="METHOD_REF"/>
      <property name="option" value="nl"/>
    </module>
    <module name="PackageName">
      <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
      <message key="name.invalidPattern"
             value="Package name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="TypeName">
      <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF,
                    ANNOTATION_DEF, RECORD_DEF"/>
      <message key="name.invalidPattern"
             value="Type name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="MemberName">
      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
      <message key="name.invalidPattern"
             value="Member name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="ParameterName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <message key="name.invalidPattern"
             value="Parameter name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="LambdaParameterName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <message key="name.invalidPattern"
             value="Lambda parameter name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="CatchParameterName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <message key="name.invalidPattern"
             value="Catch parameter name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="LocalVariableName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <message key="name.invalidPattern"
             value="Local variable name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="PatternVariableName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <message key="name.invalidPattern"
             value="Pattern variable name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="ClassTypeParameterName">
      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
      <message key="name.invalidPattern"
             value="Class type name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="RecordComponentName">
      <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
      <message key="name.invalidPattern"
               value="Record component name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="RecordTypeParameterName">
      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
      <message key="name.invalidPattern"
               value="Record type name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="MethodTypeParameterName">
      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
      <message key="name.invalidPattern"
             value="Method type name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="InterfaceTypeParameterName">
      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
      <message key="name.invalidPattern"
             value="Interface type name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="NoFinalizer"/>
    <module name="GenericWhitespace">
      <message key="ws.followed"
             value="GenericWhitespace ''{0}'' is followed by whitespace."/>
      <message key="ws.preceded"
             value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
      <message key="ws.illegalFollow"
             value="GenericWhitespace ''{0}'' should followed by whitespace."/>
      <message key="ws.notPreceded"
             value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
    </module>
    <module name="Indentation">
      <property name="basicOffset" value="2"/>
      <property name="braceAdjustment" value="2"/>
      <property name="caseIndent" value="2"/>
      <property name="throwsIndent" value="4"/>
      <property name="lineWrappingIndentation" value="4"/>
      <property name="arrayInitIndent" value="2"/>
    </module>
    <module name="AbbreviationAsWordInName">
      <property name="ignoreFinal" value="false"/>
      <property name="allowedAbbreviationLength" value="0"/>
      <property name="allowedAbbreviations" value="UI, D"/>
      <property name="tokens"
               value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, ANNOTATION_DEF, ANNOTATION_FIELD_DEF,
                    PARAMETER_DEF, VARIABLE_DEF, METHOD_DEF, PATTERN_VARIABLE_DEF, RECORD_DEF,
                    RECORD_COMPONENT_DEF"/>
    </module>
    <module name="NoWhitespaceBeforeCaseDefaultColon"/>
    <module name="OverloadMethodsDeclarationOrder"/>
    <!-- module name="ConstructorsDeclarationGrouping"/ -->
    <module name="VariableDeclarationUsageDistance"/>
    <module name="CustomImportOrder">
      <property name="sortImportsInGroupAlphabetically" value="true"/>
      <property name="separateLineBetweenGroups" value="true"/>
      <property name="customImportOrderRules" value="STATIC###THIRD_PARTY_PACKAGE"/>
      <property name="tokens" value="IMPORT, STATIC_IMPORT, PACKAGE_DEF"/>
    </module>
    <module name="MethodParamPad">
      <property name="tokens"
               value="CTOR_DEF, LITERAL_NEW, METHOD_CALL, METHOD_DEF,
                    SUPER_CTOR_CALL, ENUM_CONSTANT_DEF, RECORD_DEF"/>
    </module>
    <module name="NoWhitespaceBefore">
      <property name="tokens"
               value="COMMA, SEMI, POST_INC, POST_DEC, DOT,
                    LABELED_STAT, METHOD_REF"/>
      <property name="allowLineBreaks" value="true"/>
    </module>
    <module name="ParenPad">
      <property name="tokens"
               value="ANNOTATION, ANNOTATION_FIELD_DEF, CTOR_CALL, CTOR_DEF, DOT, ENUM_CONSTANT_DEF,
                    EXPR, LITERAL_CATCH, LITERAL_DO, LITERAL_FOR, LITERAL_IF, LITERAL_NEW,
                    LITERAL_SWITCH, LITERAL_SYNCHRONIZED, LITERAL_WHILE, METHOD_CALL,
                    METHOD_DEF, QUESTION, RESOURCE_SPECIFICATION, SUPER_CTOR_CALL, LAMBDA,
                    RECORD_DEF"/>
    </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>

    <!-- Metrics -->
    <module name="CyclomaticComplexity">
      <property name="switchBlockAsSingleDecisionPoint" value="true"/>
    </module>
    <module name="JavaNCSS"/>
    <module name="NPathComplexity"/>

    <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>
    <module name="NonEmptyAtclauseDescription"/>
    <module name="InvalidJavadocPosition"/>
    <module name="JavadocTagContinuationIndentation"/>
    <module name="SummaryJavadoc">
      <property name="forbiddenSummaryFragments"
               value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
    </module>
    <module name="JavadocParagraph">
      <property name="allowNewlineParagraph" value="false"/>
    </module>
    <module name="RequireEmptyLineBeforeBlockTagGroup"/>
    <module name="AtclauseOrder">
      <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
      <property name="target"
               value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
    </module>
    <!--
    <module name="JavadocMethod">
      <property name="accessModifiers" value="public"/>
      <property name="allowMissingParamTags" value="true"/>
      <property name="allowMissingReturnTag" value="true"/>
      <property name="allowedAnnotations" value="Override, Test"/>
      <property name="tokens" value="METHOD_DEF, CTOR_DEF, ANNOTATION_FIELD_DEF, COMPACT_CTOR_DEF"/>
    </module>
    <module name="MissingJavadocMethod">
      <property name="scope" value="protected"/>
      <property name="allowMissingPropertyJavadoc" value="true"/>
      <property name="allowedAnnotations" value="Override, Test"/>
      <property name="tokens" value="METHOD_DEF, CTOR_DEF, ANNOTATION_FIELD_DEF,
                                   COMPACT_CTOR_DEF"/>
    </module>
    <module name="SuppressionXpathSingleFilter">
      <property name="checks" value="MissingJavadocMethod"/>
      <property name="query" value="//*[self::METHOD_DEF or self::CTOR_DEF
                                 or self::ANNOTATION_FIELD_DEF or self::COMPACT_CTOR_DEF]
                                 [ancestor::*[self::INTERFACE_DEF or self::CLASS_DEF
                                 or self::RECORD_DEF or self::ENUM_DEF]
                                 [not(./MODIFIERS/LITERAL_PUBLIC)]]"/>
    </module>
    <module name="MissingJavadocType">
      <property name="scope" value="protected"/>
      <property name="tokens"
                value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF,
                      RECORD_DEF, ANNOTATION_DEF"/>
      <property name="excludeScope" value="nothing"/>
    </module>
    -->
    <module name="MethodName">
      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
      <message key="name.invalidPattern"
             value="Method name ''{0}'' must match pattern ''{1}''."/>
    </module>
    <module name="SuppressionXpathSingleFilter">
      <property name="checks" value="MethodName"/>
      <property name="query" value="//METHOD_DEF[
                                     ./MODIFIERS/ANNOTATION//IDENT[contains(@text, 'Test')]
                                   ]/IDENT"/>
      <property name="message" value="'[a-z][a-z0-9][a-zA-Z0-9]*(?:_[a-z][a-z0-9][a-zA-Z0-9]*)*'"/>
    </module>
    <module name="SingleLineJavadoc"/>
    <module name="EmptyCatchBlock">
      <property name="exceptionVariableName" value="expected"/>
    </module>
    <module name="CommentsIndentation">
      <property name="tokens" value="SINGLE_LINE_COMMENT, BLOCK_COMMENT_BEGIN"/>
    </module>
    <!-- https://checkstyle.org/filters/suppressionxpathfilter.html -->
    <module name="SuppressionXpathFilter">
      <property name="file" value="${org.checkstyle.google.suppressionxpathfilter.config}"
             default="checkstyle-xpath-suppressions.xml" />
      <property name="optional" value="true"/>
    </module>
    <module name="SuppressWarningsHolder" />
    <module name="SuppressionCommentFilter">
      <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)" />
      <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)" />
      <property name="checkFormat" value="$1" />
    </module>
    <module name="SuppressWithNearbyCommentFilter">
      <property name="commentFormat" value="CHECKSTYLE.SUPPRESS\: ([\w\|]+)"/>
      <!-- $1 refers to the first match group in the regex defined in commentFormat -->
      <property name="checkFormat" value="$1"/>
      <!-- The check is suppressed in the next line of code after the comment -->
      <property name="influenceFormat" value="1"/>
    </module>
  </module>
</module>