checkstyle.xml

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

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

<module name="Checker">
	<property name="charset" value="UTF-8" />
	<property name="fileExtensions" value="java, properties, xml" />

	<module name="JavadocPackage"></module>
	
	<!-- This permits to detect old-style eclipse formatting, which wrapped 
		@param doc. -->
	<module name="RegexpSingleline">
		<!-- \s matches whitespace character, $ matches end of line. -->
		<property name="format" value="@param [^\s]*\s*$" />
		<property name="fileExtensions" value="java" />
		<property name="message"
			value="Javadoc @ should be directly followed by the corresponding content." />
	</module>

	<module name="TreeWalker">
		<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" />
		</module>
		<module name="JavadocStyle" />

		<module name="NonEmptyAtclauseDescription" />
		<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="LineLength">
			<!-- Eclipse [built-in] has 120, but checkstyle counts 8 spaces per tab 
				(instead of 2), and eclipse wraps line with two supplementary tabs, thus 
				there’s easily 7 tabs or 7×6 = 42 supplementary spaces. -->
			<property name="max" value="162" />
			<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" />
		<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" />
		</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">
			<!-- ELLIPSIS is EOL until https://github.com/google/styleguide/issues/258 -->
			<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/259 -->
			<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]*)*$" />
			<message key="name.invalidPattern"
				value="Package name ''{0}'' must match pattern ''{1}''." />
		</module>
		<module name="TypeName">
			<message key="name.invalidPattern"
				value="Type name ''{0}'' must match pattern ''{1}''." />
		</module>
		<module name="MemberName">
			<property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$" />
			<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]*)?$" />
			<message key="name.invalidPattern"
				value="Catch parameter name ''{0}'' must match pattern ''{1}''." />
		</module>
		<module name="LocalVariableName">
			<property name="tokens" value="VARIABLE_DEF" />
			<property name="format"
				value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$" />
			<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="8" />
			<property name="braceAdjustment" value="0" />
			<property name="caseIndent" value="0" />
			<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="1" />
			<property name="allowedAbbreviations" value="MP,IMP,LE,EQ,GE" />
		</module>
		<module name="OverloadMethodsDeclarationOrder" />
		<module name="VariableDeclarationUsageDistance" />
		<module name="CustomImportOrder">
			<property name="sortImportsInGroupAlphabetically"
				value="true" />
			<property name="separateLineBetweenGroups" value="true" />
			<property name="customImportOrderRules"
				value="STATIC###STANDARD_JAVA_PACKAGE###SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE" />
			<property name="specialImportsRegExp" value="^org\." />
			<property name="thirdPartyPackageRegExp" value="^com\." />
		</module>
		<module name="MethodParamPad" />
		<module name="NoWhitespaceBefore">
			<property name="tokens"
				value="COMMA, SEMI, POST_INC, POST_DEC, DOT, ELLIPSIS, METHOD_REF" />
			<property name="allowLineBreaks" value="true" />
		</module>
		<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="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="MethodName">
			<property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$|LE|EQ|GE" />
			<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>
</module>