checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
    <property name="severity" value="warning" />
    <property name="localeLanguage" value="en" />

    <module name="FileTabCharacter">
        <property name="fileExtensions" value="java" />
    </module>

    <module name="TreeWalker">

        <!-- code cleanup -->
        <module name="UnusedImports">
            <property name="processJavadoc" value="true" />
        </module>
        <module name="RedundantImport" />
        <module name="IllegalImport" />
        <module name="EqualsHashCode" />
        <module name="SimplifyBooleanExpression" />
        <module name="OneStatementPerLine" />
        <module name="UnnecessaryParentheses" />
        <module name="SimplifyBooleanReturn" />

        <!-- style -->
        <module name="DefaultComesLast" />
        <module name="EmptyStatement" />
        <module name="ArrayTypeStyle" />
        <module name="UpperEll" />
        <module name="LeftCurly" />
        <module name="RightCurly" />
        <module name="EmptyStatement" />
        <module name="ConstantName">
            <property name="format"
                value="(^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$)|(^log$)" />
        </module>
        <module name="LocalVariableName" />
        <module name="LocalFinalVariableName" />
        <module name="MemberName" />
        <module name="ClassTypeParameterName">
            <property name="format" value="^[A-Z0-9]*$" />
        </module>
        <module name="MethodTypeParameterName">
            <property name="format" value="^[A-Z0-9]*$" />
        </module>
        <module name="PackageName" />
        <module name="ParameterName" />
        <module name="StaticVariableName" />
        <module name="TypeName" />
        <module name="AvoidStarImport" />


        <!-- whitespace -->
        <module name="GenericWhitespace" />
        <module name="NoWhitespaceBefore" />
        <module name="WhitespaceAfter" />
        <module name="NoWhitespaceAfter" />
        <module name="WhitespaceAround">
            <property name="allowEmptyConstructors"
                value="true" />
            <property name="allowEmptyMethods" value="true" />
        </module>
        <module name="MethodParamPad" />
        <module name="ParenPad" />
        <module name="TypecastParenPad" />

        <!-- locale-sensitive methods should specify locale -->
        <module name="Regexp">
            <property name="format"
                value="\.to(Lower|Upper)Case\(\)" />
            <property name="illegalPattern" value="true" />
            <property name="ignoreComments" value="true" />
        </module>
    </module>
</module>