checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
          "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
   <!-- this checker only defines the things we really do not want, not all the warnings that checkstyle would also allow -->
  <module name="SuppressWarningsFilter"/>
  <property name="charset" value="UTF-8"/>
  <property name="severity" value="error"/>
  <property name="fileExtensions" value="java, properties, rsc, xml"/>

  <!-- allow suppression of errors for certain files -->
  <module name="SuppressionFilter">
    <property name="file" value="checkstyle-suppressions.xml" />
    <property name="optional" value="true"/>
  </module>


  <!-- Whitespace -->
  <module name="FileTabCharacter"> <!-- no tabs -->
    <property name="eachLine" value="true"/>
  </module>
  <module name="RegexpSingleline">
    <property name="format" value="[^\s]\s+$"/> <!-- we only care about statements with trailing whitespace, empty lines with some whitespace we're not gointg to be picky about -->

    <property name="message" value="Remove trailing whitespace" />
    <property name="fileExtensions" value="xml, java, rsc"/>
  </module>

  <!-- java style things -->
  <module name="TreeWalker">
    <module name="OuterTypeFilename"/> <!-- make sure the name of the file is the same as the class -->
    <module name="AvoidEscapedUnicodeCharacters">
      <!-- avoid escapes of unicode chars where we can just write the unicode char in a string -->
      <property name="allowEscapesForControlCharacters" value="true"/>
      <property name="allowByTailComment" value="true"/>
      <property name="allowNonPrintableEscapes" value="true"/>
    </module>
    <module name="NeedBraces"> <!-- make sure that {} are always required, also for single line statements -->
      <property name="tokens" value="LITERAL_DO, LITERAL_ELSE, LITERAL_FOR, LITERAL_IF, LITERAL_WHILE"/>
    </module>
    <module name="OneStatementPerLine"/>
    <module name="FallThrough"/> <!-- can be relieved by explicitly adding a comment that mentions fall[s]?through-->
    <module name="ModifierOrder"/>
    <module name="NoFinalizer"/>

    <module name="Indentation"> <!-- make sure indents happen at a predictable pattern-->
      <property name="basicOffset" value="4"/>
      <property name="braceAdjustment" value="4"/>
      <property name="caseIndent" value="4"/>
      <property name="throwsIndent" value="4"/>
      <property name="lineWrappingIndentation" value="4"/>
      <property name="arrayInitIndent" value="4"/>
    </module>

  </module>

</module>