conf/checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.1//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_1.dtd">

<!-- Checkstyle configuration that checks the commons-configuration coding conventions -->

<module name="Checker">
    <property name="localeLanguage" value="en"/>

    <!-- Checks that a package.html file exists for each package.     -->
    <!-- See http://checkstyle.sf.net/config_javadoc.html#PackageHtml -->
    <module name="PackageHtml"/>

    <!-- 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"/>


    <module name="TreeWalker">

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

        <!-- Checks for Javadoc comments.                     -->
        <!-- See http://checkstyle.sf.net/config_javadoc.html -->
        <module name="JavadocMethod">
            <property name="allowUndeclaredRTE" value="true"/>
        </module>
        <module name="JavadocType">
            <property name="authorFormat" value="\S"/>
        </module>
        <module name="JavadocVariable"/>


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


        <!-- Checks for Headers                              -->
        <!-- See http://checkstyle.sf.net/config_header.html -->
        <module name="Header">
            <property name="headerFile" value="${basedir}/conf/HEADER.txt"/>
            <property name="ignoreLines" value="2"/>
        </module>

        <!-- Following interprets the header file as regular expressions. -->
        <!-- <module name="RegexpHeader"/>                                -->


        <!-- 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"/>


        <!-- Checks for Size Violations.                    -->
        <!-- See http://checkstyle.sf.net/config_sizes.html -->
        <module name="FileLength"/>
        <module name="LineLength">
            <property name="max" value="120"/>
        </module>
        <module name="MethodLength"/>
        <module name="ParameterNumber"/>


        <!-- Checks for whitespace                               -->
        <!-- See http://checkstyle.sf.net/config_whitespace.html -->
        <module name="EmptyForIteratorPad"/>
        <module name="NoWhitespaceAfter"/>
        <module name="NoWhitespaceBefore"/>
        <module name="OperatorWrap"/>
        <module name="ParenPad"/>
        <module name="TabCharacter"/>
        <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">
            <property name="option" value="nl"/>
        </module>
        <module name="NeedBraces"/>
        <module name="RightCurly">
            <property name="option" value="alone"/>
        </module>


        <!-- Checks for common coding problems               -->
        <!-- See http://checkstyle.sf.net/config_coding.html -->
        <module name="CovariantEquals"/>
        <module name="DoubleCheckedLocking"/>
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <module name="IllegalInstantiation"/>
        <module name="InnerAssignment"/>
        <module name="MagicNumber"/>
        <module name="MissingSwitchDefault"/>
        <module name="RedundantThrows"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>
        <module name="StringLiteralEquality"/>
        <module name="SuperClone"/>
        <module name="SuperFinalize"/>
        <module name="IllegalType"/>
        <module name="DeclarationOrder"/>
        <module name="ExplicitInitialization"/>
        <module name="DefaultComesLast"/>
        <module name="FallThrough"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="UnnecessaryParentheses"/>

        <!-- Checks for class design                         -->
        <!-- See http://checkstyle.sf.net/config_design.html -->
        <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="GenericIllegalRegexp">
            <property name="format" value="\s+$"/>
            <property name="message" value="Line has trailing spaces."/>
        </module>
        <module name="TodoComment"/>
        <module name="UpperEll"/>

    </module>

</module>