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="RegexpSingleline">
        <!-- \s matches whitespace character, $ matches end of line. -->
        <property name="format" value="\s+$"/>
        <property name="message" value="Line has trailing spaces."/>
    </module>

    <module name="TreeWalker">

        <property name="cacheFile" value="${checkstyle.cache.file}"/>

        <!-- ensure we have tabs only -->
        <module name="RegexpSinglelineJava">
            <property name="format" value="^\t* +\t*\S"/>
            <property name="message" value="Line has leading space characters; indentation should be performed with tabs only."/>
            <property name="ignoreComments" value="true"/>
        </module>

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

        <!-- Checks for common coding problems               -->
        <!-- Disabled until http://sourceforge.net/tracker/?func=detail&aid=2843447&group_id=29721&atid=397078 is fixed-->
        <!--<module name="DoubleCheckedLocking"/>-->
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <module name="IllegalInstantiation"/>
        <module name="RedundantThrows">
            <property name="allowUnchecked" value="true"/>
        </module>

        <!-- Miscellaneous other checks.                   -->
        <module name="UpperEll"/>
        <module name="PackageAnnotation"/>
        <module name="CovariantEquals"/>
        <module name="ArrayTypeStyle"/>

    </module>

</module>