checkstyle.xml

<?xml version="1.0"?>
<!--
  ~  Copyright (c) 2019, Salesforce.com, Inc.
  ~  All rights reserved.
  ~  Licensed under the BSD 3-Clause license.
  ~  For full license text, see LICENSE.txt file in the repo root  or https://opensource.org/licenses/BSD-3-Clause
  -->

<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
    <!-- Checks that a package-info.java file exists for each package.     -->
    <!-- See http://checkstyle.sf.net/config_javadoc.html#JavadocPackage -->

    <!--<module name="JavadocPackage"/>-->

    <!-- Checks whether files end with a new line.                        -->
    <!-- See http://checkstyle.sf.net/config_misc.html#NewlineAtEndOfFile -->
    <!--<module name="NewlineAtEndOfFile"/>-->

    <!-- Checks that property files contain the same keys.         -->
    <!-- See http://checkstyle.sf.net/config_misc.html#Translation -->
    <module name="Translation"/>

    <!-- Checks for Size Violations.                    -->
    <!-- See http://checkstyle.sf.net/config_sizes.html -->
    <module name="FileLength"/> <!-- by default set to 2000 lines-->

    <!-- Checks for whitespace                               -->
    <!-- See http://checkstyle.sf.net/config_whitespace.html -->
    <module name="FileTabCharacter"/> <!-- spaces not tabs -->

    <!-- Miscellaneous other checks.                   -->
    <!-- See http://checkstyle.sf.net/config_misc.html -->
    <module name="RegexpSingleline">
        <property name="format" value="\s+$"/>
        <property name="minimum" value="0"/>
        <property name="maximum" value="0"/>
        <property name="message" value="Line has trailing spaces."/>
    </module>

    <!-- Checks for Headers                                -->
    <!-- See http://checkstyle.sf.net/config_header.html   -->
    <module name="Header">
        <property name="headerFile" value="checkstyle-header.txt"/>
        <property name="fileExtensions" value="java"/>
    </module>

    <module name="TreeWalker">
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
            <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
            <property name="checkFormat" value="$1"/>
        </module>

        <module name="SuppressWithNearbyCommentFilter">
            <property name="commentFormat" value="CHECKSTYLE DISABLE ([\w\|]+) FOR (-?\d+) LINES"/>
            <property name="checkFormat" value="$1"/>
            <property name="influenceFormat" value="$2"/>
        </module>

        <!-- Checks for Javadoc comments.                     -->
        <!-- See http://checkstyle.sf.net/config_javadoc.html -->
        <!--<module name="JavadocMethod"/>-->
        <module name="JavadocType"/>
        <!--<module name="JavadocVariable"/>-->
        <module name="JavadocStyle"/>

        <!-- Checks for Naming Conventions.                  -->
        <!-- See http://checkstyle.sf.net/config_naming.html -->
        <module name="ConstantName"/>
        <module name="LocalFinalVariableName"/>
        <module name="LocalVariableName"/>

        <module name="MemberName">
            <!-- camel case variables and all upper case constants (with underscores) -->
            <property name="format" value="^[a-z][a-zA-Z0-9]*|[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$"/>
        </module>

        <module name="MethodName"/>
        <module name="PackageName"/>
        <module name="ParameterName"/>
        <module name="StaticVariableName"/>
        <module name="TypeName"/>

        <!-- Checks for imports                              -->
        <!-- See http://checkstyle.sf.net/config_import.html -->
        <!--<module name="AvoidStarImport"/>-->
        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
        <module name="RedundantImport"/>
        <module name="UnusedImports">
            <property name="processJavadoc" value="false"/>
        </module>

        <!-- Checks for Size Violations.                    -->
        <!-- See http://checkstyle.sf.net/config_sizes.html -->
        <!--
                <module name="LineLength"/>
        -->
        <module name="MethodLength"/>
        <module name="ParameterNumber"/>


        <!-- Checks for whitespace                               -->
        <!-- See http://checkstyle.sf.net/config_whitespace.html -->
        <module name="EmptyForIteratorPad"/>
        <module name="GenericWhitespace"/>
        <module name="MethodParamPad"/>
        <module name="NoWhitespaceAfter"/>
        <module name="NoWhitespaceBefore"/>
        <module name="OperatorWrap">
            <property name="option" value="eol"/>
        </module>
        <module name="ParenPad"/>
        <module name="TypecastParenPad"/>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround"/>


        <!-- Modifier Checks                                    -->
        <!-- See http://checkstyle.sf.net/config_modifiers.html -->
        <module name="ModifierOrder"/>
        <module name="RedundantModifier"/>

        <!-- Checks for blocks. You know, those {}'s         -->
        <!-- See http://checkstyle.sf.net/config_blocks.html -->
        <module name="AvoidNestedBlocks"/>
        <module name="EmptyBlock"/>
        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly"/>

        <!-- Checks for common coding problems               -->
        <!-- See http://checkstyle.sf.net/config_coding.html -->
        <!--<module name="AvoidInlineConditionals"/>-->
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <!--<module name="HiddenField"/>-->
        <module name="IllegalInstantiation"/>
        <module name="InnerAssignment"/>
        <module name="MagicNumber"/>
        <module name="MissingSwitchDefault"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>

        <!-- Checks for class design                         -->
        <!-- See http://checkstyle.sf.net/config_design.html -->
        <!--<module name="DesignForExtension"/>-->
        <module name="FinalClass"/>
        <module name="HideUtilityClassConstructor"/>
        <module name="InterfaceIsType"/>
        <module name="VisibilityModifier">
            <property name="protectedAllowed" value="true"/>
        </module>



        <!-- Miscellaneous other checks.                   -->
        <!-- See http://checkstyle.sf.net/config_misc.html -->
        <module name="ArrayTypeStyle"/>
        <!--<module name="FinalParameters"/>-->
        <!--<module name="TodoComment"/>-->
        <module name="UpperEll"/>
        <module name="Indentation"/>

        <module name="DescendantToken">
            <property name="tokens" value="EQUAL,NOT_EQUAL"/>
            <property name="limitedTokens" value="STRING_LITERAL"/>
            <property name="maximumNumber" value="0"/>
            <property name="maximumDepth" value="1"/>
            <property name="maximumMessage" value="Don't compare strings with ==, use .equals() instead"/>
        </module>

        <module name="DescendantToken">
            <property name="tokens" value="EMPTY_STAT"/>
            <property name="limitedTokens" value="EMPTY_STAT"/>
            <property name="maximumNumber" value="0"/>
            <property name="maximumDepth" value="0"/>
            <property name="maximumMessage" value="Empty statement is not allowed."/>
        </module>

        <module name="DescendantToken">
            <property name="tokens" value="LITERAL_SWITCH"/>
            <property name="limitedTokens" value="LITERAL_SWITCH"/>
            <property name="maximumNumber" value="0"/>
            <property name="minimumDepth" value="1"/>
            <property name="maximumMessage" value="Don't put switch statements inside other switch statements."/>
        </module>

        <module name="Regexp">
            <property name="format" value="@Subscribe\s+private void"/>
            <property name="illegalPattern" value="true"/>
            <property name="ignoreComments" value="true"/>
            <property name="message" value="Event handlers must be public"/>
        </module>
    </module>
</module>