checkstyle-config.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
  "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
  "https://checkstyle.org/dtds/configuration_1_3.dtd">
<!--

  Checkstyle configuration that checks the sun coding conventions from:

    - the Java Language Specification at
      https://docs.oracle.com/javase/specs/jls/se11/html/index.html

    - the Sun Code Conventions at https://www.oracle.com/technetwork/java/codeconvtoc-136057.html

    - the Javadoc guidelines at
      https://www.oracle.com/technetwork/java/javase/documentation/index-137868.html

    - the JDK Api documentation https://docs.oracle.com/en/java/javase/11/

    - some best practices

  Checkstyle is very configurable. Be sure to read the documentation at
  http://checkstyle.sourceforge.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.

-->

<module name="Checker">
  <!--
      If you set the basedir property below, then all reported file
      names will be relative to the specified directory. See
      https://checkstyle.org/5.x/config.html#Checker

      <property name="basedir" value="${basedir}"/>
  -->

  <property name="fileExtensions" value="java"/>


  <module name="SuppressionFilter">
    <property name="file" value="checkstyle-suppressions.xml"/>
    <property name="optional" value="false"/>
  </module>
  <!-- Excludes all 'module-info.java' files              -->
  <!-- See https://checkstyle.org/config_filefilters.html -->
  <module name="BeforeExecutionExclusionFileFilter">
    <property name="fileNamePattern" value="module\-info\.java$"/>
  </module>

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

  <!-- Checks that property files contain the same keys.         -->
  <!-- See http://checkstyle.sourceforge.net/config_misc.html#Translation -->
  <module name="Translation"/>

  <!-- Checks for Size Violations.                    -->
  <!-- See http://checkstyle.sourceforge.net/config_sizes.html -->
  <module name="FileLength"/>

  <!-- Checks for whitespace                               -->
  <!-- See http://checkstyle.sourceforge.net/config_whitespace.html -->
  <module name="FileTabCharacter"/>

  <!-- Miscellaneous other checks.                   -->
  <!-- See http://checkstyle.sourceforge.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>

  <!-- Checks for Headers                                -->
  <!-- See http://checkstyle.sourceforge.net/config_header.html   -->
  <!-- <module name="Header"> -->
  <!--   <property name="headerFile" value="${checkstyle.header.file}"/> -->
  <!--   <property name="fileExtensions" value="java"/> -->
  <!-- </module> -->

  <module name="TreeWalker">

    <!-- Checks for Javadoc comments.                     -->
    <!-- See http://checkstyle.sourceforge.net/config_javadoc.html -->
    <!--<module name="JavadocStyle"/>-->

    <!-- Checks for Naming Conventions.                  -->
    <!-- See http://checkstyle.sourceforge.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 imports                              -->
    <!-- See http://checkstyle.sourceforge.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.sourceforge.net/config_sizes.html -->
    <module name="MethodLength"/>
    <module name="ParameterNumber"/>

    <!-- Checks for whitespace                               -->
    <!-- See http://checkstyle.sourceforge.net/config_whitespace.html -->
    <!--<module name="EmptyForIteratorPad"/>-->
    <module name="GenericWhitespace"/>
    <module name="MethodParamPad"/>
    <!--<module name="NoWhitespaceAfter"/>-->
    <module name="NoWhitespaceBefore"/>
    <module name="OperatorWrap"/>
    <!--<module name="ParenPad"/>-->
    <module name="TypecastParenPad"/>
    <module name="WhitespaceAfter"/>
    <!--<module name="WhitespaceAround"/>-->

    <!-- Modifier Checks                                    -->
    <!-- See http://checkstyle.sourceforge.net/config_modifiers.html -->
    <module name="ModifierOrder"/>

    <!-- Checks for blocks. You know, those {}'s         -->
    <!-- See http://checkstyle.sourceforge.net/config_blocks.html -->
    <module name="AvoidNestedBlocks"/>
    <module name="EmptyBlock"/>
    <!--<module name="LeftCurly"/>-->
    <module name="NeedBraces"/>
    <!--<module name="RightCurly"/>-->

    <!-- Checks for common coding problems               -->
    <!-- See http://checkstyle.sourceforge.net/config_coding.html -->
    <module name="EmptyStatement"/>
    <module name="EqualsHashCode"/>
    <!--<module name="HiddenField"/>-->
    <module name="IllegalInstantiation"/>
    <module name="InnerAssignment"/>
    <!--<module name="MagicNumber"/>-->
    <module name="MissingSwitchDefault"/>
    <module name="MultipleVariableDeclarations"/>
    <module name="SimplifyBooleanExpression"/>
    <module name="SimplifyBooleanReturn"/>

    <!-- Checks for class design                         -->
    <!-- See http://checkstyle.sourceforge.net/config_design.html -->
    <!--<module name="DesignForExtension"/>-->
    <module name="FinalClass"/>
    <module name="HideUtilityClassConstructor"/>
    <module name="InterfaceIsType"/>
    <!--<module name="VisibilityModifier"/>-->

    <!-- Miscellaneous other checks.                   -->
    <!-- See http://checkstyle.sourceforge.net/config_misc.html -->
    <module name="ArrayTypeStyle"/>
    <!--<module name="FinalParameters"/>-->
    <!--
         openEQUELLA seems to have a lot of historical TODO comments - about 202. It'd be handy
         to keep them around as a form of documentation, as it provides insight when trying to
         understand what's going on. Hopefully code reviews though will stop people attempting
         to add new TODO comments.
    -->
    <!--<module name="TodoComment"/>-->
    <module name="UpperEll"/>
  </module>
</module>