checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
	"https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
	<module name="SuppressWarningsFilter"/>

	<module name="SeverityMatchFilter">
		<property name="severity" value="info"/>
		<property name="acceptOnMatch" value="false"/>
	</module>

	<module name="NewlineAtEndOfFile">
		<property name="lineSeparator" value="lf_cr_crlf"/>
	</module>

	<module name="TreeWalker">

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

		<!-- This only fails if at least 4 spaces have been used somewhere -->
		<!-- Generally, this allows to still use the "smart tabs" feature for certain code alignments -->
		<module name="RegexpSinglelineJava">
			<property name="format" value="^\t* {4,}"/>
			<property name="message" value="Indent must use tab characters"/>
			<property name="ignoreComments" value="true"/>
		</module>

		<!-- Needed to suppress warnings if needed -->
		<module name="SuppressWarningsHolder"/>
		<module name="SuppressWithNearbyCommentFilter"/>
		<module name="SuppressionCommentFilter"/>

		<!-- Block checks -->
		<!-- Nested blocks are allowed -->
		<!--
		<module name="AvoidNestedBlocks">
			<property name="allowInSwitchCase" value="true"/>
		</module>
		-->
		<module name="LeftCurly"/>
		<module name="RightCurly"/>


		<!-- Class design -->
		<module name="DesignForExtension">
			<property name="ignoredAnnotations"
					  value="After, AfterClass, Before, BeforeClass, Test, Override, Provides"/>
		</module>

		<module name="FinalClass"/>
		<module name="HideUtilityClassConstructor"/>
		<module name="InnerTypeLast"/>
		<module name="InterfaceIsType"/>
		<module name="MutableException"/>
		<module name="OneTopLevelClass"/>
		<module name="ThrowsCount"/>
		<module name="VisibilityModifier">
			<property name="protectedAllowed" value="true"/>
			<property name="packageAllowed" value="true"/>
			<property name="allowPublicFinalFields" value="true"/>
			<property name="allowPublicImmutableFields" value="true"/>
		</module>


		<!-- Coding -->
		<module name="AvoidDoubleBraceInitialization"/>
		<module name="AvoidNoArgumentSuperConstructorCall"/>
		<module name="CovariantEquals"/>
		<module name="DeclarationOrder">
			<property name="ignoreModifiers" value="true"/>
			<property name="ignoreConstructors" value="true"/>
		</module>
		<module name="DefaultComesLast"/>
		<module name="EmptyStatement"/>
		<module name="FallThrough"/>
		<module name="IllegalCatch"/>
		<module name="IllegalThrows"/>
		<module name="IllegalType">
			<property name="ignoredMethodNames" value="getInstance"/>
		</module>

		<module name="IllegalType">
			<property name="illegalClassNames" value="org.apache.log4j.Logger,org.slf4j.Logger"/>
			<message key="illegal.type" value="Use new Logging API: org.apache.logging.log4j.Logger / LogManager"/>
		</module>

		<module name="IllegalType">
			<property name="illegalClassNames" value="java.util.Random"/>
			<message key="illegal.type" value="Use java.util.SplittableRandom for better performance and randomness"/>
		</module>

		<module name="IllegalType">
			<property name="illegalClassNames" value="com.google.inject.Singleton"/>
			<message key="illegal.type" value="Use javax.inject.Singleton"/>
		</module>

		<module name="MultipleVariableDeclarations"/>
		<module name="NestedForDepth">
			<!-- Very high because some code violates it -->
			<property name="max" value="7"/>
		</module>
		<module name="NestedTryDepth">
			<property name="max" value="2"/>
		</module>
		<module name="NoArrayTrailingComma"/>
		<module name="NoClone"/>
		<module name="NoEnumTrailingComma"/>
		<module name="NoFinalizer"/>
		<module name="OneStatementPerLine"/>
		<module name="OverloadMethodsDeclarationOrder"/>
		<module name="PackageDeclaration"/>
		<module name="SimplifyBooleanExpression"/>
		<module name="SimplifyBooleanReturn"/>
		<module name="StringLiteralEquality"/>
		<module name="UnnecessarySemicolonAfterOuterTypeDeclaration"/>
		<module name="UnnecessarySemicolonAfterTypeMemberDeclaration"/>
		<module name="UnnecessarySemicolonInEnumeration"/>
		<module name="UnnecessarySemicolonInTryWithResources"/>


		<!-- Imports -->
		<module name="RedundantImport"/>
		<module name="UnusedImports"/>


		<!-- JavaDoc -->
		<module name="AtclauseOrder"/>
		<module name="InvalidJavadocPosition"/>
		<module name="JavadocContentLocationCheck"/>
		<module name="JavadocStyle">
			<property name="checkEmptyJavadoc" value="true"/>
		</module>
		<module name="JavadocType">
			<property name="scope" value="protected"/>
			<property name="allowMissingParamTags" value="true"/>
		</module>
		<module name="JavadocMethod">
			<property name="accessModifiers" value="public, protected"/>
			<property name="allowMissingParamTags" value="true"/>
			<property name="allowMissingReturnTag" value="true"/>
		</module>
		<module name="MissingJavadocMethod">
			<property name="scope" value="protected"/>
			<property name="allowMissingPropertyJavadoc" value="true"/>
			<property name="allowedAnnotations" value="Override,Inject,Provides"/>
			<!-- Relaxed check on common names -->
			<property name="ignoreMethodNamesRegex" value="^(is|get|set|remove|add|new|create|main|run|call).*$"/>
			<!-- Don't check constructors -->
			<property name="tokens" value="METHOD_DEF,ANNOTATION_FIELD_DEF"/>
		</module>
		<module name="MissingJavadocType">
			<property name="scope" value="public"/>
			<property name="skipAnnotations" value="Generated,Command,CommandLine.Command"/>
		</module>
		<module name="NonEmptyAtclauseDescription"/>


		<!-- Metrics -->
		<module name="JavaNCSS">
			<property name="methodMaximum" value="100"/>
			<property name="classMaximum" value="800"/>
			<property name="fileMaximum" value="1000"/>
		</module>
		<module name="CyclomaticComplexity">
			<property name="switchBlockAsSingleDecisionPoint" value="true"/>
			<property name="max" value="32"/>
		</module>


		<!-- Miscellaneous -->
		<module name="ArrayTypeStyle"/>
		<module name="AvoidEscapedUnicodeCharacters"/>
		<module name="OuterTypeFilename"/>
		<module name="TodoComment">
			<!-- High priority comments -->
			<property name="format" value="(yyyyyy|FIXME)"/>
			<message key="todo.match" value="Address this issue or reduce severity"/>
		</module>
		<module name="UpperEll"/>
		<module name="TrailingComment"/>

		<module name="Regexp">
			<property name="format" value="((System\.(out|err)\.print)|printStackTrace)"/>
			<property name="ignoreComments" value="true"/>
			<property name="illegalPattern" value="true"/>
			<property name="message" value="No printing to console, use a logger."/>
		</module>

		<!-- Modifier -->
		<module name="ModifierOrder"/>
		<module name="RedundantModifier"/>

		<!-- Naming conventions -->
		<module name="AbbreviationAsWordInName"/>
		<module name="ClassTypeParameterName"/>
		<module name="ConstantName">
			<!-- Only public constants are checked -->
			<property name="applyToProtected" value="false"/>
			<property name="applyToPackage" value="false"/>
			<property name="applyToPrivate" value="false"/>
		</module>
		<module name="IllegalIdentifierName"/>
		<module name="InterfaceTypeParameterName"/>
		<module name="LambdaParameterName"/>
		<module name="LocalFinalVariableName"/>
		<module name="LocalVariableName">
			<property name="allowOneCharVarInForLoop" value="true"/>
			<!-- Underscores are allowed -->
			<property name="format" value="^[a-z][a-zA-Z0-9_]*$"/>
		</module>
		<module name="MemberName"/>
		<module name="MethodName"/>
		<module name="MethodTypeParameterName"/>
		<module name="PackageName"/>
		<module name="ParameterName">
			<!-- Underscores are allowed -->
			<property name="format" value="^[a-z][a-zA-Z0-9_]*$"/>
		</module>
		<module name="RecordComponentName" />
		<module name="RecordTypeParameterName"/>
		<module name="StaticVariableName"/>
		<module name="TypeName"/>


		<!-- Whitespace -->
		<module name="EmptyForInitializerPad"/>
		<module name="EmptyForIteratorPad"/>
		<module name="MethodParamPad"/>
		<module name="NoLineWrap"/>
		<!--
		<module name="NoWhitespaceAfter"/>
		<module name="NoWhitespaceBefore"/>
		<module name="OperatorWrap"/>
		-->
		<module name="SingleSpaceSeparator"/>
		<module name="WhitespaceAfter"/>
		<module name="TypecastParenPad"/>
		<module name="EmptyLineSeparator">
			<property name="tokens" value="PACKAGE_DEF,CLASS_DEF,INTERFACE_DEF,ENUM_DEF,METHOD_DEF"/>
		</module>

		<module name="Regexp">
			<!-- Trailing whitespaces in comments are allowed -->
			<property name="format" value="^(?!(?:[ \t]*?(?:\/?\*\*?|\/\/)[\S \t]+?|[ \t]+$))[\S \t]+[ \t]+$"/>
			<property name="illegalPattern" value="true"/>
			<property name="message" value="Trailing whitespace"/>
		</module>

	</module>
</module>