checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
    Copyright 2018 The MIT Internet Trust Consortium
   
    Portions copyright 2011-2013 The MITRE Corporation
   
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
   
      http://www.apache.org/licenses/LICENSE-2.0
   
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
 -->
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<!-- This is a checkstyle configuration file. For descriptions of what the 
	following rules do, please see the checkstyle configuration page at http://checkstyle.sourceforge.net/config.html -->

<!-- Adapted from google-api-java-client -->

<module name="Checker">

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

	<module name="RegexpSingleline">
		<!-- Checks that FIXME is not used in comments. TODO is preferred. -->
		<property name="format" value="((//.*)|(\*.*))FIXME"/>
		<property name="message" value='TODO is preferred to FIXME.'/>
		<property name="severity" value="warning"/>
	</module>

	<!-- All Java AST specific tests live under TreeWalker module. -->
	<module name="TreeWalker">

		<!-- IMPORT CHECKS -->

		<module name="RedundantImport">
			<!-- Checks for redundant import statements. -->
			<property name="severity" value="error"/>
		</module>

		<module name="ImportOrder">
			<!-- Checks for out of order import statements. -->

			<property name="severity" value="warning"/>
			<!-- This ensures that static imports go first. -->
			<property name="option" value="top"/>
			<property name="tokens" value="STATIC_IMPORT, IMPORT"/>
		</module>

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

		<module name="UnusedImports"/>

		<!-- JAVADOC CHECKS -->

		<!-- Checks for Javadoc comments. -->
		<!-- See http://checkstyle.sf.net/config_javadoc.html -->

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

		<!-- NAMING CHECKS -->

		<!-- Item 38 - Adhere to generally accepted naming conventions -->

		<module name="PackageName">
			<!-- Validates identifiers for package names against the supplied expression. -->
			<!-- Here the default checkstyle rule restricts package name parts to 
				seven characters, this is not in line with common practice at Google. -->
			<property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="TypeNameCheck">
			<!-- Validates static, final fields against the expression "^[A-Z][a-zA-Z0-9]*$". -->
			<metadata name="altname" value="TypeName"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="ConstantNameCheck">
			<!-- Validates non-private, static, final fields against the supplied 
				public/package final fields "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$". -->
			<metadata name="altname" value="ConstantName"/>
			<property name="applyToPublic" value="true"/>
			<property name="applyToProtected" value="true"/>
			<property name="applyToPackage" value="true"/>
			<property name="applyToPrivate" value="false"/>
			<property name="format" value="^([A-Z][A-Z0-9]*(_[A-Z0-9]+)*|FLAG_.*)$"/>
			<message key="name.invalidPattern"
				value="Variable ''{0}'' should be in ALL_CAPS (if it is a constant) or be private (otherwise)."/>
			<property name="severity" value="warning"/>
		</module>

		<module name="StaticVariableNameCheck">
			<!-- Validates static, non-final fields against the supplied expression 
				"^[a-z][a-zA-Z0-9]*_?$". -->
			<metadata name="altname" value="StaticVariableName"/>
			<property name="applyToPublic" value="true"/>
			<property name="applyToProtected" value="true"/>
			<property name="applyToPackage" value="true"/>
			<property name="applyToPrivate" value="true"/>
			<property name="format" value="^[a-z][a-zA-Z0-9]*_?$"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="MemberNameCheck">
			<!-- Validates non-static members against the supplied expression. -->
			<metadata name="altname" value="MemberName"/>
			<property name="applyToPublic" value="true"/>
			<property name="applyToProtected" value="true"/>
			<property name="applyToPackage" value="true"/>
			<property name="applyToPrivate" value="true"/>
			<property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="MethodNameCheck">
			<!-- Validates identifiers for method names. -->
			<metadata name="altname" value="MethodName"/>
			<property name="format" value="^[a-z][a-zA-Z0-9]*(_[a-zA-Z0-9]+)*$"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="ParameterName">
			<!-- Validates identifiers for method parameters against the expression 
				"^[a-z][a-zA-Z0-9]*$". -->
			<property name="severity" value="warning"/>
		</module>

		<module name="LocalFinalVariableName">
			<!-- Validates identifiers for local final variables against the expression 
				"^[a-z][a-zA-Z0-9]*$". -->
			<property name="severity" value="warning"/>
		</module>

		<module name="LocalVariableName">
			<!-- Validates identifiers for local variables against the expression 
				"^[a-z][a-zA-Z0-9]*$". -->
			<property name="severity" value="warning"/>
		</module>

		<!-- LENGTH and CODING CHECKS -->

		<module name="LineLength">
			<!-- Checks if a line is too long. -->
			<property name="max"
				value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.max}"
				default="250"/>
			<property name="severity" value="warning"/>

			<!-- 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="LeftCurly">
			<!-- Checks for placement of the left curly brace ('{'). -->
			<property name="severity" value="warning"/>
		</module>

		<module name="RightCurly">
			<!-- Checks right curlies on CATCH, ELSE, and TRY blocks are on the same 
				line. e.g., the following example is fine: <pre> if { ... } else </pre> -->
			<!-- This next example is not fine: <pre> if { ... } else </pre> -->
			<property name="option" value="same"/>
			<property name="severity" value="warning"/>
		</module>

		<!-- Checks for braces around if and else blocks -->
		<module name="NeedBraces">
			<property name="severity" value="warning"/>
			<property name="tokens"
				value="LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO"/>
		</module>

		<module name="UpperEll">
			<!-- Checks that long constants are defined with an upper ell. -->
			<property name="severity" value="error"/>
		</module>

		<module name="FallThrough">
			<!-- Warn about falling through to the next case statement. Similar to 
				javac -Xlint:fallthrough, but the check is suppressed if a single-line comment 
				on the last non-blank line preceding the fallen-into case contains 'fall 
				through' (or some other variants which we don't publicized to promote consistency). -->
			<property name="reliefPattern"
				value="fall through|Fall through|fallthru|Fallthru|falls through|Falls through|fallthrough|Fallthrough|No break|NO break|no break|continue on"/>
			<property name="severity" value="error"/>
		</module>

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

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

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

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

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

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

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

		<module name="MultipleStringLiterals">
			<property name="allowedDuplicates" value="1"/>
			<property name="severity" value="warning"/>
		</module>

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

		<module name="PackageDeclaration"/>

		<!-- COMPLEXITY CHECKS -->

		<module name="BooleanExpressionComplexity">
			<property name="max" value="10"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="CyclomaticComplexity">
			<property name="max" value="10"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="NPathComplexity">
			<property name="max" value="200"/>
			<property name="severity" value="warning"/>
		</module>

		<!-- MODIFIERS CHECKS -->

		<module name="ModifierOrder">
			<!-- Warn if modifier order is inconsistent with JLS3 8.1.1, 8.3.1, and 
				8.4.3. The prescribed order is: public, protected, private, abstract, static, 
				final, transient, volatile, synchronized, native, strictfp -->
		</module>


		<!-- WHITESPACE CHECKS -->

		<module name="WhitespaceAround">
			<!-- Checks that various tokens are surrounded by whitespace. This includes 
				most binary operators and keywords followed by regular or curly braces. -->
			<property name="tokens"
				value="ASSIGN, BAND, BAND_ASSIGN, BOR, 
				BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN, 
				EQUAL, GE, GT, LAND, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE, 
				LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN, 
				LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS, 
				MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION, 
				SL, SL_ASSIGN, SR_ASSIGN, STAR, STAR_ASSIGN"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="WhitespaceAfter">
			<!-- Checks that commas, semicolons and typecasts are followed by whitespace. -->
			<property name="tokens" value="COMMA, SEMI, TYPECAST"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="NoWhitespaceAfter">
			<!-- Checks that there is no whitespace after various unary operators. 
				Linebreaks are allowed. -->
			<property name="tokens"
				value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS, UNARY_PLUS"/>
			<property name="allowLineBreaks" value="true"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="NoWhitespaceBefore">
			<!-- Checks that there is no whitespace before various unary operators. 
				Linebreaks are allowed. -->
			<property name="tokens" value="SEMI, DOT, POST_DEC, POST_INC"/>
			<property name="allowLineBreaks" value="true"/>
			<property name="severity" value="warning"/>
		</module>

		<module name="ParenPad">
			<!-- Checks that there is no whitespace before close parens or after open 
				parens. -->
			<property name="severity" value="warning"/>
		</module>

	</module>
</module>