Google Java Checkstyle modified using tabs (mapped to 2 spaces) and 120 line length

checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
          "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<!--
    Checkstyle configuration that checks the Google coding conventions from:
    -  Google Java Style
       https://google-styleguide.googlecode.com/svn-history/r130/trunk/javaguide.html
    Checkstyle is very configurable. Be sure to read the documentation at
    http://checkstyle.sf.net (or in your downloaded distribution).
    Most Checks are configurable, be sure to consult the documentation.
    To completely disable a check, just comment it out or delete it from the file.
    Authors: Max Vetrenko, Ruslan Diachenko, Roman Ivanov.
 -->

<module name = "Checker">
    <property name="charset" value="UTF-8"/>

    <property name="severity" value="warning"/>

    <property name="fileExtensions" value="java, properties, xml"/>
    <!-- Checks for whitespace                               -->
    <!-- See http://checkstyle.sf.net/config_whitespace.html -->
        <module name="FileTabCharacter">
            <property name="eachLine" value="false"/>
        </module>

    <module name="TreeWalker">
        <property name="tabWidth" value="2"/>
        <module name="OuterTypeFilename"/>
        <module name="IllegalTokenText">
            <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
            <property name="format" value="\\u00(08|09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
            <property name="message" value="Avoid using corresponding octal or Unicode escape."/>
        </module>
        <module name="AvoidEscapedUnicodeCharacters">
            <property name="allowEscapesForControlCharacters" value="true"/>
            <property name="allowByTailComment" value="true"/>
            <property name="allowNonPrintableEscapes" value="true"/>
        </module>
        <module name="LineLength">
            <property name="max" value="120"/>
            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
        </module>
        <module name="AvoidStarImport"/>
        <module name="OneTopLevelClass"/>
        <module name="NoLineWrap"/>
        <module name="EmptyBlock">
            <property name="option" value="TEXT"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
        </module>
        <module name="NeedBraces"/>
        <module name="LeftCurly">
            <property name="maxLineLength" value="120"/>
        </module>
        <module name="RightCurly"/>
        <module name="RightCurly">
            <property name="option" value="alone"/>
            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO, STATIC_INIT, INSTANCE_INIT"/>
        </module>
        <module name="WhitespaceAround">
            <property name="allowEmptyConstructors" value="true"/>
            <property name="allowEmptyMethods" value="true"/>
            <property name="allowEmptyTypes" value="true"/>
            <property name="allowEmptyLoops" value="true"/>
            <message key="ws.notFollowed"
             value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
             <message key="ws.notPreceded"
             value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
        </module>
        <module name="OneStatementPerLine"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="ArrayTypeStyle"/>
        <module name="MissingSwitchDefault"/>
        <module name="FallThrough"/>
        <module name="UpperEll"/>
        <module name="ModifierOrder"/>
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="DOT"/>
            <property name="option" value="nl"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="COMMA"/>
            <property name="option" value="EOL"/>
        </module>
        <module name="PackageName">
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
            <message key="name.invalidPattern"
             value="Package name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="TypeName">
            <message key="name.invalidPattern"
             value="Type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MemberName">
            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
            <message key="name.invalidPattern"
             value="Member name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="ParameterName">
            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
            <message key="name.invalidPattern"
             value="Parameter name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="LocalVariableName">
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
            <property name="allowOneCharVarInForLoop" value="true"/>
            <message key="name.invalidPattern"
             value="Local variable name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="ClassTypeParameterName">
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
            <message key="name.invalidPattern"
             value="Class type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MethodTypeParameterName">
            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
            <message key="name.invalidPattern"
             value="Method type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="NoFinalizer"/>
        <module name="GenericWhitespace">
            <message key="ws.followed"
             value="GenericWhitespace ''{0}'' is followed by whitespace."/>
             <message key="ws.preceded"
             value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
             <message key="ws.illegalFollow"
             value="GenericWhitespace ''{0}'' should followed by whitespace."/>
             <message key="ws.notPreceded"
             value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
        </module>
        <module name="Indentation">
            <property name="basicOffset" value="2"/>
            <property name="braceAdjustment" value="0"/>
            <property name="caseIndent" value="2"/>
            <property name="throwsIndent" value="4"/>
            <property name="lineWrappingIndentation" value="4"/>
            <property name="arrayInitIndent" value="2"/>
        </module>
        <module name="AbbreviationAsWordInName">
            <property name="ignoreFinal" value="false"/>
            <property name="allowedAbbreviationLength" value="1"/>
        </module>
        <module name="OverloadMethodsDeclarationOrder"/>
        <module name="VariableDeclarationUsageDistance"/>
        <module name="CustomImportOrder">
            <property name="specialImportsRegExp" value="com.google"/>
            <property name="sortImportsInGroupAlphabetically" value="true"/>
            <property name="customImportOrderRules" value="STATIC###SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE###STANDARD_JAVA_PACKAGE"/>
        </module>
        <module name="MethodParamPad"/>
        <module name="OperatorWrap">
            <property name="option" value="NL"/>
            <property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR "/>
        </module>
        <module name="AnnotationLocation">
            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
        </module>
        <module name="AnnotationLocation">
            <property name="tokens" value="VARIABLE_DEF"/>
            <property name="allowSamelineMultipleAnnotations" value="true"/>
        </module>
        <module name="NonEmptyAtclauseDescription"/>
        <module name="JavadocTagContinuationIndentation"/>
        <module name="SummaryJavadocCheck">
            <property name="forbiddenSummaryFragments" value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
        </module>
        <module name="JavadocParagraph"/>
        <module name="AtclauseOrder">
            <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
            <property name="target" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
        </module>
        <module name="JavadocMethod">
            <property name="scope" value="public"/>
            <property name="allowMissingParamTags" value="true"/>
            <property name="allowMissingThrowsTags" value="true"/>
            <property name="allowMissingReturnTag" value="true"/>
            <property name="minLineCount" value="2"/>
            <property name="allowedAnnotations" value="Override, Test"/>
            <property name="allowThrowsTagsForSubclasses" value="true"/>
        </module>
        <module name="MethodName">
            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
            <message key="name.invalidPattern"
             value="Method name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="SingleLineJavadoc">
            <property name="ignoreInlineTags" value="false"/>
        </module>
        <module name="EmptyCatchBlock">
            <property name="exceptionVariableName" value="expected"/>
        </module>
        <module name="CommentsIndentation"/>
    </module>
</module>

I'm confused about the FileTabCharacter. That module is used to ensure that there are no tabs. But, later on, you use RegexpSinglelineJava to ensure that tab characters are used for indentation?

They both actually do the same thing. The regex for RegexpSinglelineJava if it matches (a tab), will throw an error. That's redundant because as you said FileTabCharacter does that already. I've removed the regex module.