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">
  
  <!--
  
      CHECKS
      
  -->

  <!-- Require a new line at the end of all source files. This was more of a
       requirement from CVS, but since some editors add one automatically we
       should require it anyway in order to avoid obfuscated diffs -->
  <module name="NewlineAtEndOfFile" />

  <!-- Disallow trailing white space since some editors remove it automatically
       resulting in obfuscated diffs -->
  <module name="RegexpSingleline">
    <property name="format" value="\s+$" />
    <property name="message" value="Line has trailing spaces." />
  </module>
  
  <!-- Require package-info.java for all packages -->
  <module name="JavadocPackage" />

  <!--  Use header file template passed in from Maven -->
  <!--module name="RegexpHeader">
    <property name="headerFile" value="${checkstyle.header.file}" />
    <property name="multiLines" value="1,2,3" />
  </module-->

  <!--  Unlike Sun conventions, align length with LineLength -->
  <!--
  TODO: needs many changes to make it work.
  Previous configuration may have been ignored.
  <module name="LineLength">
    <property name="max" value="120"/>
  </module>
  -->

  <!-- TODO: check if SuppressWithNearbyCommentFilter did the same before -->
  <module name="SuppressionFilter">
    <property name="file" value="suppressions.xml" />
  </module>

  <module name="TreeWalker">
 
    <!-- Enable result caching -->
    <!--property name="cacheFile" value="${checkstyle.cache.file}" /-->

  <!--

      SUPPRESSION FILTERS

  -->
  <!-- Toggle Checkstyle on/off
  
      // @Checkstyle:off
      ... ignored
      // @Checkstyle:on
  
  -->
  <module name="SuppressionCommentFilter">
    <property name="offCommentFormat" value="@Checkstyle:off" />
    <property name="onCommentFormat" value="@Checkstyle:on" />
  </module>

  <!--  Instruct Checkstyle to ignore a specific check for a whole file
  
      // @Checkstyle:ignore AvoidNestedBlocks
  
  -->
  <module name="SuppressWithNearbyCommentFilter">
    <property name="commentFormat" value="@Checkstyle:ignore ([\w\|]+)"/>
    <property name="checkFormat" value="$1"/>
    <property name="influenceFormat" value="1000000" />
  </module>

  <!--  Instruct Checkstyle to ignore next line
  
      // @Checkstyle:ignore
      ... ignored
      ... checked
  
  -->
  <module name="SuppressWithNearbyCommentFilter">
    <property name="commentFormat" value="@Checkstyle:ignore" />
    <property name="influenceFormat" value="1" />
  </module>

  <!--  Instruct Checkstyle to ignore next N lines (-ve means previous lines)
  
      // @Checkstyle:ignoreFor 2
      ... ignored
      ... ignored
      ... checked
  
  -->
  <module name="SuppressWithNearbyCommentFilter">
    <property name="commentFormat" value="@Checkstyle:ignoreFor (\d+)" />
    <property name="influenceFormat" value="$1" />
  </module>

    <!-- 
    
        JAVADOC COMMENTS
    
    -->

    <!--  Require Javadoc for all types regardless of scope -->
    <module name="JavadocType">
      <property name="scope" value="protected" />
    </module>
    
    <!--  Require valid Javadoc for all protected and public members -->
    <module name="JavadocMethod">
      <property name="scope" value="protected" />
    </module>
    <module name="JavadocVariable">
      <property name="scope" value="protected" />
    </module>
    
    <!--  If Javadoc is present then it must be valid -->
    <module name="JavadocStyle">
      <property name="scope" value="protected" />
      <property name="checkEmptyJavadoc" value="true" />
      <property name="endOfSentenceFormat" value="([.?!:][ \t\n\r\f&lt;])|([.?!:]$)" />
    </module>

    <!--  Javadoc should not contain author annotations -->
    <module name="WriteTag">
      <property name="tag" value="@author"/>
      <property name="tagFormat" value="\S"/>
      <!-- Ignore when not present -->
      <property name="severity" value="ignore"/>
      <!-- Warn when present -->
      <property name="tagSeverity" value="error"/>
    </module>

    <!--
    
        NAMING CONVENTIONS
    
    -->
    
    <!--  As per Sun conventions -->
    <module name="ClassTypeParameterName">
      <property name="format" value="^[A-Z][0-9]*$" />
    </module>
    <module name="LocalFinalVariableName" />
    <module name="LocalVariableName" />
    <module name="MemberName" />
    <module name="MethodName" />
    <module name="MethodTypeParameterName" >
      <property name="format" value="^[A-Z][0-9]*$" />
    </module>
    <module name="PackageName" />
    <module name="ParameterName" />
    <module name="TypeName" />

    <!-- As per Sun convention except also allowing "logger" or "xxxLogger"
         since some people don't like references to "LOGGER" shouting out all
         over their code -->
    <module name="ConstantName">
      <property name="format" value="^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$|^[a-z][a-zA-Z0-9]*Logger$|^logger$"/>
    </module>
    
    <!--
    
        IMPORTS
    
    -->
    
    <!-- Unlike Sun conventions, allow wild-card static imports -->
    <module name="AvoidStarImport">
      <property name="allowStaticMemberImports" value="true" />
    </module>
    
    <!--  As per Sun conventions -->
    <module name="IllegalImport" />
    <module name="RedundantImport" />
    <module name="UnusedImports">
      <property name="processJavadoc" value="true" />
    </module>

    <!--
    
        SIZE VIOLATIONS
    
    -->
    
    <!--  Restrict classes to one per file -->
    <module name="OuterTypeNumber" />
    
    <!--
    
        WHITE SPACE
    
    -->
    
    <!--  As per Sun conventions -->
    <module name="EmptyForIteratorPad" />
    <module name="MethodParamPad" />
    <!--  Unlike Sun conventions, allow whitespace after array initializer -->
    <module name="NoWhitespaceAfter">
      <property name="tokens" value="BNOT,DEC,DOT,INC,LNOT,UNARY_MINUS,UNARY_PLUS" />
    </module>
    <module name="OperatorWrap" />
    <module name="ParenPad" />
    <module name="TypecastParenPad" />
    <module name="WhitespaceAfter" />

    <!--
    
        MODIFIERS
    
    -->
    
    <!--  As per Sun conventions -->
    <!-- Do we want these? They are a bit pedantic.
    <module name="ModifierOrder" />
    <module name="RedundantModifier" />
    -->
 
    <!--
    
        BLOCKS
    
    -->
    
    <!--  Unlike Sun conventions, allow nested blocks in switch statements
          since these allow developers to declare case-scope local variables -->
    <module name="AvoidNestedBlocks">
      <property name="allowInSwitchCase" value="true" />
    </module>
    
    <!--  Unlike Sun conventions we'll allow empty blocks, but only if they are
          documented -->
    <module name="EmptyBlock">
      <property name="option" value="text" />
    </module>
    
    <!--  As per Sun conventions -->
    <module name="NeedBraces" />
    <module name="RightCurly" />

    <!--
    
        CODING
    
    -->

    <!--  As per Sun conventions -->
    <module name="EmptyStatement" />
    <module name="EqualsHashCode" />    
    <module name="IllegalInstantiation" />
    <module name="SimplifyBooleanExpression" />
    <module name="SimplifyBooleanReturn" />
    
    <!--  Additional checks -->
    
    <!--  String literal equality is never an optimization since the
          String.equals() will check for this and will be inlined -->
    <module name="StringLiteralEquality" />
    <!-- Check package name is present and matches directory name as well -->
    <module name="PackageDeclaration" />
    <!--  Require one statement per line -->
    <module name="OneStatementPerLine" />

    <!--
    
        CLASS DESIGN
    
    -->

    <!--  As per Sun conventions -->
    <module name="FinalClass" />
    <module name="HideUtilityClassConstructor" />
    
    <!--
    
        MISC
    
    -->

    <!--  As per Sun conventions -->
    <module name="ArrayTypeStyle" />
    <module name="UpperEll" />
    
    <!--  Require that file name corresponds to class name -->
    <module name="OuterTypeFilename" />

  </module>
</module>