check_style.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://checkstyle.sourceforge.net/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="fileExtensions" value="java, properties, xml"/>
    <module name="RegexpHeader">
        <property name="headerFile" value="microsoft.header"/>
    </module>
    <!-- Checks for whitespace                              
     See http://checkstyle.sf.net/config_whitespace.html -->
    <module name="FileTabCharacter">
        <property name="eachLine" value="true"/>
    </module>
    
    <!-- No trailing spaces allowed -->
    <module name="RegexpSingleline">
        <property name="format" value="\s+$"/>
        <property name="message" value="Line has trailing spaces."/>
    </module>

    <!-- CRLF is not allowed -->
    <module name="RegexpMultiline">
        <property name="format" value="(?s:(\r\n|\r).*)"/>
        <property name="message" value="CRLF and CR line endings are prohibited, but this file uses them."/>
    </module>

    <module name="LineLengthCheck">
        <property name="fileExtensions" value="java" />
        <!-- Checks if a line is too long. -->
        <property name="max" value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.max}" default="160"/>
        <property name="severity" value="error"/>

        <!--
          The default ignore pattern exempts the following elements:
            - import statements
            - long URLs inside comments
        -->

        <property name="ignorePattern"
                  value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.ignorePattern}"
                  default="^(package .*;\s*)|(import .*;\s*)|( *\* *https?://.*)$"/>
    </module>

    <module name="TreeWalker">
        <!-- Default CheckStyle Whitespace rules seem reasonable to use. -->
        <module name="EmptyForIteratorPad"/>
        <module name="MethodParamPad"/>
        <module name="NoWhitespaceAfter"/>
        <module name="NoWhitespaceBefore"/>
        <module name="OperatorWrap"/>
        <module name="ParenPad"/>
        <module name="TypecastParenPad"/>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround"/>

        <!-- Modifier Order as specified by Java Language Specifications. -->
        <module name="ModifierOrder"/>

        <!-- Empty blocks allowed, as long as they have explicit comments stating why they are empty.  -->
        <module name="EmptyBlock">
            <property name="option" value="text"/>
        </module>


        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly"/>

        <!-- Added some coding problems as INFO.  Up to developer to react to them. -->
        <module name="CovariantEquals">
            <property name="severity" value="info"/>
        </module>
        <!-- Only apply this to local variables; Designers seem to prefer using same parameter names as class members. -->
        <module name="HiddenField">
            <property name="tokens" value="VARIABLE_DEF"/>
        </module>

        <!-- No multiple assignement in a single line. -->
        <module name="InnerAssignment"/>
        <module name="RedundantImport" />
        <module name="UnusedImports"/>

        <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"/>
        <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="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"/>
        </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"/>
            <property name="allowMultipleEmptyLines" value="false"/>
            <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>
            <property name="tokens" value="VARIABLE_DEF, METHOD_DEF"/>
        </module>
        <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">
            <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]*)*$"/>
            <message key="name.invalidPattern"
                     value="Package name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="TypeName">
            <message key="name.invalidPattern"
                     value="Type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MemberName">
            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
            <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]*)?$"/>
            <message key="name.invalidPattern"
                     value="Parameter name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="CatchParameterName">
            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
            <message key="name.invalidPattern"
                     value="Catch parameter name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="LocalVariableName">
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
            <message key="name.invalidPattern"
                     value="Local variable name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="ClassTypeParameterName">
            <property name="format" value="(^[A-Z][0-9]?)$|([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="4"/>
            <property name="braceAdjustment" value="0"/>
            <property name="caseIndent" value="4"/>
            <property name="throwsIndent" value="4"/>
            <property name="lineWrappingIndentation" value="4"/>
            <property name="arrayInitIndent" value="4"/>
        </module>
        <module name="OverloadMethodsDeclarationOrder"/>
        <module name="VariableDeclarationUsageDistance"/>
        <module name="CustomImportOrder">
            <property name="customImportOrderRules"
                      value="STATIC###STANDARD_JAVA_PACKAGE###SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE"/>
            <property name="specialImportsRegExp" value="^org\."/>
            <property name="thirdPartyPackageRegExp" value="^com\."/>
            <property name="sortImportsInGroupAlphabetically" value="true"/>
            <property name="separateLineBetweenGroups" value="true"/>
            <property name="severity" value="info"/>
        </module>
        <module name="MethodParamPad"/>
        <module name="ParenPad"/>
        <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 "/>
        </module>
        <module name="AnnotationLocation">
            <property name="id" value="AnnotationLocationMostCases"/>
            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, 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="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="allowMissingReturnTag" value="true"/>
            <property name="allowedAnnotations" value="Override, Test"/>
        </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"/>
        </module>
        <module name="CommentsIndentation"/>
        <module name="EmptyStatement"/>
        <module name="StringLiteralEquality"/>
         <!-- Developer should probably bring up this issue with designer if ever it occurs. -->
        <module name="EqualsHashCode">
            <property name="severity" value="info" />
        </module>
        <!-- Only apply this to local variables; Designers seem to prefer using same parameter names as class members. -->
        <module name="HiddenField">
            <property name="tokens" value="VARIABLE_DEF"/>
        </module>
        
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>
    </module>
</module>