config/checkstyle/checkstyle.xml

<?xml version="1.0"?>
<!--
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this work except in compliance with the License.
You may obtain a copy of the License in the LICENSE file, or at:

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

<!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 sun coding conventions from:

    - the Java Language Specification at
      http://java.sun.com/docs/books/jls/second_edition/html/index.html

    - the Sun Code Conventions at http://java.sun.com/docs/codeconv/

    - the Javadoc guidelines at
      http://java.sun.com/j2se/javadoc/writingdoccomments/index.html

    - the JDK Api documentation http://java.sun.com/j2se/docs/api/index.html

    - some best practices

  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.

  Finally, it is worth reading the documentation.

  TODO(wfarner): Iterate on this file to converge towards the google style checks provided
  by checkstyle:
  https://github.com/checkstyle/checkstyle/blob/master/src/main/resources/google_checks.xml
-->

<module name="Checker">
  <!--
      If you set the basedir property below, then all reported file
      names will be relative to the specified directory. See
      http://checkstyle.sourceforge.net/config.html#Checker
      <property name="basedir" value="${basedir}"/>
        -->

  <!-- Checks whether files end with a new line.                        -->
  <!-- See http://checkstyle.sf.net/config_misc.html#NewlineAtEndOfFile -->
  <module name="NewlineAtEndOfFile"/>

  <!-- Disallows multiple sequential newlines. -->
  <module name="RegexpMultiline">
    <property name="format" value="\n{3,}"/>
    <property name="message" value="File contains a sequence of empty lines."/>
  </module>

  <!-- Checks for whitespace                               -->
  <!-- See http://checkstyle.sf.net/config_whitespace.html -->
  <module name="FileTabCharacter">
    <property name="eachLine" value="true"/>
  </module>

  <!-- Miscellaneous other checks.                   -->
  <!-- See http://checkstyle.sf.net/config_misc.html -->
  <module name="RegexpSingleline">
    <property name="format" value="\s+$"/>
    <property name="minimum" value="0"/>
    <property name="maximum" value="0"/>
    <property name="message" value="Line has trailing spaces."/>
  </module>

  <module name="RegexpHeader">
    <property name="headerFile" value="config/checkstyle/apache.header.regex"/>
    <property name="fileExtensions" value="java"/>
  </module>

  <module name="TreeWalker">
    <property name="tabWidth" value="2"/>

    <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>

    <!-- needed for SuppressWithNearbyCommentFilter -->
    <module name="FileContentsHolder"/>

    <!-- Annotations -->
    <module name="AnnotationUseStyle"/>
    <module name="MissingDeprecated"/>
    <module name="MissingOverride"/>
    <module name="PackageAnnotation"/>

    <module name="JavadocType">
      <property name="excludeScope" value="private"/>
    </module>
    <module name="JavadocStyle">
      <property name="checkEmptyJavadoc" value="true"/>
    </module>
    <module name="JavadocVariable">
      <property name="excludeScope" value="private"/>
    </module>

    <!-- Checks for Naming Conventions.                  -->
    <module name="ClassTypeParameterName"/>
    <module name="ConstantName"/>
    <module name="LocalFinalVariableName">
      <!-- allow VAR_NAME and varName in local final variables,
      leave it up to user to use them appropriately depending on whether
      or not the variable is A_CONSTANT_VARIBLE, or aMutableVariable.
      -->
      <property name="format" value="^(([a-z][a-zA-Z0-9]*)|([A-Z][A-Z0-9]*(_[A-Z0-9]+)*))$" />
    </module>
    <module name="LocalVariableName"/>
    <module name="MemberName"/>
    <module name="MethodTypeParameterName"/>
    <module name="PackageName"/>
    <module name="ParameterName"/>
    <module name="StaticVariableName"/>
    <module name="TypeName"/>

    <!-- Checks for imports                              -->
    <!-- See http://checkstyle.sf.net/config_import.html -->
    <module name="AvoidStarImport">
      <property name="excludes" value="org.junit.Assert"/>
      <property name="excludes" value="java.util.*"/>
    </module>
    <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
    <module name="RedundantImport"/>
    <module name="UnusedImports"/>
    <module name="ImportOrder">
      <property name="groups"
        value="/^javax?\./,scala,com,net,org"/>
      <property name="ordered" value="true"/>
      <property name="separated" value="true"/>
      <property name="option" value="bottom"/>
      <message key="import.ordering"
        value="Wrong order for ''{0}'' import. Order should be: java, javax, scala, com, net, org.
        Each group should be separated by a single blank line." />
    </module>

    <!-- Checks for Size Violations.                    -->
    <!-- See http://checkstyle.sf.net/config_sizes.html -->
    <module name="LineLength">
      <property name="max" value="100"/>
      <property name="ignorePattern" value="^import"/>
    </module>
    <module name="OuterTypeNumber"/>

    <!-- Checks for whitespace                               -->
    <!-- See http://checkstyle.sf.net/config_whitespace.html -->
    <module name="EmptyForInitializerPad"/>
    <module name="EmptyForIteratorPad"/>
    <module name="MethodParamPad"/>
    <module name="NoWhitespaceAfter"/>
    <module name="NoWhitespaceBefore"/>
    <module name="OperatorWrap"/>
    <module name="ParenPad"/>
    <module name="TypecastParenPad"/>
    <module name="WhitespaceAfter"/>
    <module name="WhitespaceAround">
      <!-- Intentionally excludes RCURLY (default) since it trips on anonymous
           inner class declarations when chained with a method call.
      -->
      <property name="tokens" value="ASSIGN,BAND,BAND_ASSIGN,BOR,BOR_ASSIGN,BSR,BSR_ASSIGN,
        BXOR,BXOR_ASSIGN,COLON,DIV,DIV_ASSIGN,EQUAL,GE,GT,LAND,
        LCURLY,LE,LITERAL_ASSERT,LITERAL_CATCH,LITERAL_DO,
        LITERAL_ELSE,LITERAL_FINALLY,LITERAL_FOR,LITERAL_IF,
        LITERAL_RETURN,LITERAL_SYNCHRONIZED,LITERAL_TRY,
        LITERAL_WHILE,LOR,LT,MINUS,MINUS_ASSIGN,MOD,MOD_ASSIGN,
        NOT_EQUAL,PLUS,PLUS_ASSIGN,QUESTION,SL,SLIST,SL_ASSIGN,
        SR,SR_ASSIGN,STAR,STAR_ASSIGN,TYPE_EXTENSION_AND"/>
    </module>

    <!-- 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">
      <!-- Allow comments to satisfy the EmptyBlock check -->
      <property name="option" value="text"/>
    </module>
    <module name="LeftCurly"/>
    <module name="NeedBraces"/>
    <module name="RightCurly"/>

    <!-- Checks for common coding problems               -->
    <!-- See http://checkstyle.sf.net/config_coding.html -->
    <module name="CovariantEquals"/>
    <module name="EmptyStatement"/>
    <module name="EqualsAvoidNull"/>
    <module name="EqualsHashCode"/>
    <module name="HiddenField">
      <property name="ignoreConstructorParameter" value="true"/>
      <property name="ignoreSetter" value="true"/>
      <property name="setterCanReturnItsClass" value="true"/>
    </module>

    <!-- disallow calling constructors on these classes
         calling factories is the only way to create these objects
    -->
    <module name="IllegalInstantiation">
      <property name="classes" value="java.lang.Boolean"/>
    </module>
    <module name="IllegalToken">
      <property name="tokens" value="LITERAL_NATIVE"/>
    </module>
    <module name="InnerAssignment"/>
    <module name="MissingSwitchDefault"/>
    <module name="ModifiedControlVariable"/>
    <module name="SimplifyBooleanExpression"/>
    <module name="SimplifyBooleanReturn"/>
    <module name="StringLiteralEquality"/>
    <module name="SuppressWarnings"/>
    <module name="NestedForDepth">
      <property name="max" value="2"/>
    </module>
    <module name="NoClone"/>
    <module name="NoFinalizer"/>
    <module name="SuperClone"/>
    <module name="SuperFinalize"/>
    <module name="PackageDeclaration" />
    <module name="ParameterAssignment"/>
    <module name="DefaultComesLast"/>
    <module name="FallThrough"/>
    <module name="MultipleVariableDeclarations"/>
    <module name="UnnecessaryParentheses"/>
    <module name="OneStatementPerLine"/>

    <module name="FinalClass"/>
    <module name="HideUtilityClassConstructor"/>
    <module name="InterfaceIsType"/>
    <module name="MutableException"/>

    <!-- Miscellaneous other checks.                   -->
    <!-- See http://checkstyle.sf.net/config_misc.html -->
    <module name="ArrayTypeStyle"/>
    <module name="UpperEll"/>
    <module name="ArrayTypeStyle"/>
    <module name="OuterTypeFilename"/>

    <!-- Discourage use of System.exit() -->
    <module name="RegexpSinglelineJava">
      <property name="format" value="System.exit"/>
      <property name="ignoreComments" value="true"/>
      <property name="message"
        value="Don't System.exit(), throw a RuntimeException()" />
    </module>
  </module>

  <module name="SuppressionFilter">
    <property name="file" value="config/checkstyle/suppressions.xml"/>
  </module>
</module>