checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN"
                        "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">

<module name="Checker">
    <module name="TreeWalker">

        <module name="MissingOverride"/>
        <module name="PackageAnnotation"/>
        <module name="SuppressWarnings"/>
        <module name="SuppressWarningsHolder"/>

        <!-- Blocks -->
        <module name="EmptyBlock">
            <property name="option" value="text"/>
        </module>
        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly"/>

        <!-- Class Design -->
        <module name="MutableException"/>
        <module name="OneTopLevelClass"/>
        <module name="ThrowsCount">
            <property name="max" value="3"/>
        </module>

        <!-- Coding -->
        <module name="CovariantEquals"/>
        <module name="DefaultComesLast">
            <property name="skipIfLastAndSharedWithCase" value="true"/>
        </module>
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <module name="FallThrough"/>
        <module name="IllegalInstantiation">
            <property name="classes" value="java.lang.Boolean, java.lang.Integer, java.lang.Long, java.lang.Short, java.lang.Byte, java.lang.Double, java.lang.Float, java.lang.Character"/>
        </module>
        <!-- Forbid goto -->
        <module name="IllegalToken"/>
        <module name="IllegalTokenText">
            <property name="tokens" value="NUM_INT,NUM_LONG"/>
            <property name="format" value="^0[^lx]"/>
            <property name="ignoreCase" value="true"/>
            <property name="message" value="Avoid using octal numbers"/>
        </module>
        <module name="ModifiedControlVariable"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="NestedTryDepth">
            <property name="max" value="2"/>
        </module>
        <module name="NoFinalizer"/>
        <module name="OneStatementPerLine"/>
        <module name="PackageDeclaration"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>
        <module name="StringLiteralEquality"/>
        <module name="SuperFinalize"/>

        <!-- Imports -->
        <module name="AvoidStarImport"/>
        <!-- IDEA style -->
        <module name="CustomImportOrder">
            <property name="customImportOrderRules"
                      value="THIRD_PARTY_PACKAGE###SPECIAL_IMPORTS###STANDARD_JAVA_PACKAGE###STATIC"/>
            <property name="specialImportsRegExp" value="^javax\."/>
            <property name="standardPackageRegExp" value="^java\."/>
            <property name="sortImportsInGroupAlphabetically" value="true"/>
            <property name="separateLineBetweenGroups" value="false"/>
        </module>
        <module name="RedundantImport"/>
        <module name="UnusedImports">
            <property name="processJavadoc" value="true"/>
        </module>

        <!-- Miscellaneous -->
        <module name="ArrayTypeStyle"/>
        <module name="OuterTypeFilename"/>
        <module name="UpperEll"/>

        <!-- Naming Conventions -->
        <module name="CatchParameterName"/>
        <module name="InterfaceTypeParameterName">
            <property name="format" value="^[A-Z0-9_]+$"/>
        </module>
        <module name="LocalFinalVariableName"/>
        <module name="LocalVariableName"/>
        <module name="MemberName"/>
        <module name="PackageName"/>
        <module name="ParameterName">
             <property name="format" value="^__?|[a-z][a-zA-Z0-9]*$"/>
         </module>
        <module name="TypeName"/>

        <!-- Size Violations -->
        <module name="MethodCount"/>
        <module name="MethodLength"/>
        <module name="OuterTypeNumber"/>
        <!-- Whitespace -->
        <module name="EmptyForInitializerPad"/>
        <module name="EmptyForIteratorPad"/>
        <module name="MethodParamPad">
            <property name="option" value="nospace"/>
        </module>
        <module name="GenericWhitespace"/>
        <module name="NoLineWrap"/>
        <module name="NoWhitespaceAfter">
            <property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS, UNARY_PLUS"/>
        </module>
        <module name="NoWhitespaceBefore">
            <property name="allowLineBreaks" value="true"/>
        </module>
        <module name="ParenPad"/>
        <module name="SeparatorWrap">
            <property name="tokens" value="COMMA"/>
            <property name="option" value="eol"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="DOT"/>
            <property name="option" value="nl"/>
        </module>
        <module name="SingleSpaceSeparator"/>
        <module name="TypecastParenPad"/>
        <module name="WhitespaceAround">
            <property name="allowEmptyConstructors" value="true"/>
            <property name="allowEmptyLambdas" value="true"/>
            <property name="allowEmptyMethods" value="true"/>
            <property name="allowEmptyTypes" value="true"/>
        </module>
    </module>

    <!-- The tab character is forbidden in the source files -->
    <module name="FileTabCharacter">
        <property name="eachLine" value="false"/>
    </module>
    <module name="NewlineAtEndOfFile"/>

    <!-- Uses annotations to suppress audit events -->
    <module name="SuppressWarningsFilter"/>

    <!-- Detects duplicated keys in properties files -->
    <module name="UniqueProperties"/>

    <!-- Suppressions -->
    <module name="SuppressionFilter">
        <property name="file" value="${checkstyle.suppressions.file}" default=""/>
    </module>

    <!-- Generated files -->
    <module name="BeforeExecutionExclusionFileFilter">
        <property name="fileNamePattern"
                  value="(Bad|Trail)Events\.java$"/>
    </module>

</module>