java/dev/checkstyle/checkstyle.xml

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  ~    http://www.apache.org/licenses/LICENSE-2.0
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<!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
    http://checkstyle.sf.net (or in your downloaded distribution).

    To completely disable a check, just comment it out or delete it from the file.

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

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

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

    <property name="fileExtensions" value="java, properties, xml"/>

    <!-- Arrow specific modules -->

    <module name="Header">
      <property name="headerFile" value="${checkstyle.header.file}"/>
    </module>

    <module name="SuppressionFilter">
      <property name="file" value="${checkstyle.suppressions.file}"/>
    </module>

    <module name="NewlineAtEndOfFile"/>

    <!--
    If you wish to turn off checking for a section of code, you can put a comment in the source
    before and after the section, with the following syntax:
    // checkstyle:off no.XXX (such as checkstyle.off: NoFinalizer)
    ...  // stuff that breaks the styles
    // checkstyle:on
    -->
    <module name="SuppressionCommentFilter">
      <property name="offCommentFormat" value="checkstyle:off: ([\w\|]+)"/>
      <property name="onCommentFormat" value="checkstyle:on: ([\w\|]+)"/>
      <property name="checkFormat" value="$1"/>
    </module>

    <!-- Google style modules -->

    <!-- Checks for whitespace                               -->
    <!-- See http://checkstyle.sf.net/config_whitespace.html -->
    <module name="FileTabCharacter">
      <property name="eachLine" value="true"/>
    </module>

    <module name="TreeWalker">
        <module name="OuterTypeFilename"/>
        <module name="IllegalTokenText">
            <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
            <property name="format" value="\\u00(08|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="Avoid using corresponding octal or Unicode escape."/>
        </module>
        <module name="AvoidEscapedUnicodeCharacters">
            <property name="allowEscapesForControlCharacters" value="true"/>
            <property name="allowByTailComment" value="true"/>
            <property name="allowNonPrintableEscapes" value="true"/>
        </module>
        <module name="LineLength">
            <property name="max" value="120"/>
            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
        </module>
        <module name="OneTopLevelClass"/>
        <module name="NoLineWrap"/>
        <module name="EmptyBlock">
            <property name="option" value="TEXT"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
        </module>
        <module name="NeedBraces"/>
        <module name="LeftCurly">
            <property name="maxLineLength" value="100"/>
        </module>
        <module name="RightCurly"/>
        <module name="RightCurly">
            <property name="option" value="alone"/>
            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO, STATIC_INIT, INSTANCE_INIT"/>
        </module>
        <module name="WhitespaceAround">
            <property name="allowEmptyConstructors" value="true"/>
            <property name="allowEmptyMethods" value="true"/>
            <property name="allowEmptyTypes" value="true"/>
            <property name="allowEmptyLoops" value="true"/>
            <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="OneStatementPerLine"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="ArrayTypeStyle"/>
        <module name="MissingSwitchDefault"/>
        <module name="FallThrough"/>
        <module name="UpperEll"/>
        <module name="ModifierOrder"/>
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="DOT"/>
            <property name="option" value="nl"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="COMMA"/>
            <property name="option" value="EOL"/>
        </module>
        <module name="PackageName">
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
            <message key="name.invalidPattern"
             value="Package name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="TypeName">
            <message key="name.invalidPattern"
             value="Type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MemberName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*|[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$"/>
            <message key="name.invalidPattern"
             value="Member name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="ParameterName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
            <message key="name.invalidPattern"
             value="Parameter name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="CatchParameterName">
            <property name="format" value="^(e|t|ex|[a-z]e|[a-z][a-z][a-zA-Z]+)$"/>
            <message key="name.invalidPattern"
             value="Catch parameter name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="LocalVariableName">
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
            <property name="allowOneCharVarInForLoop" value="true"/>
            <message key="name.invalidPattern"
             value="Local variable name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="ClassTypeParameterName">
            <property name="format" value="(^[A-Z]+[0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
            <message key="name.invalidPattern"
             value="Class type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MethodTypeParameterName">
            <property name="format" value="(^[A-Z]+[0-9]?)$|([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="0"/>
            <property name="caseIndent" value="2"/>
            <property name="throwsIndent" value="4"/>
            <property name="lineWrappingIndentation" value="4"/>
            <property name="arrayInitIndent" value="2"/>
        </module>
        <module name="OverloadMethodsDeclarationOrder"/>
        <module name="VariableDeclarationUsageDistance"/>
        <module name="AvoidStarImport">
            <property name="allowStaticMemberImports" value="true"/>
        </module>
        <module name="ImportOrder">
            <property name="groups" value="java,javax,org,com"/>
            <property name="ordered" value="true"/>
            <property name="separated" value="true"/>
            <property name="option" value="top"/>
            <property name="sortStaticImportsAlphabetically" value="true"/>
        </module>
        <module name="MethodParamPad"/>
        <module name="OperatorWrap">
            <property name="option" value="eol"/>
            <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 "/>
        </module>
        <module name="AnnotationLocation">
            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
        </module>
        <module name="AnnotationLocation">
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="allowSamelineMultipleAnnotations" value="true"/>
        </module>
        <module name="NonEmptyAtclauseDescription"/>
        <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"/>
        <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="scope" value="public"/>
            <property name="allowMissingParamTags" value="true"/>
            <property name="allowMissingThrowsTags" value="true"/>
            <property name="allowMissingReturnTag" value="true"/>
            <property name="minLineCount" value="2"/>
            <property name="allowedAnnotations" value="Override, Test"/>
            <property name="allowThrowsTagsForSubclasses" value="true"/>
            <!-- This seems partially broken under JDK >= 9. -->
            <property name="suppressLoadErrors" value="true"/>
            <property name="ignoreMethodNamesRegex" value="main"/>
        </module>
        <module name="JavadocType">
            <property name="scope" value="public"/>
        </module>
        <module name="JavadocType">
            <property name="scope" value="protected"/>
        </module>
        <module name="JavadocType">
            <property name="scope" value="package"/>
        </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="SingleLineJavadoc">
            <property name="ignoreInlineTags" value="false"/>
        </module>
        <module name="EmptyCatchBlock">
            <property name="exceptionVariableName" value="expected|ignore"/>
        </module>
        <module name="CommentsIndentation"/>
        <!-- needed so that filters can access file contents -->
        <module name="FileContentsHolder"/>
        <module name="UnusedImports">
            <property name="severity" value="error"/>
            <property name="processJavadoc" value="true"/>
            <message key="import.unused"
                     value="Unused import: {0}."/>
        </module>
        <module name="RedundantModifier">
            <!-- Checks for redundant modifiers on various symbol definitions -->
            <property name="tokens" value="VARIABLE_DEF, ANNOTATION_FIELD_DEF, INTERFACE_DEF, CLASS_DEF, ENUM_DEF, METHOD_DEF"/>
        </module>
    </module>
</module>