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">

  <!-- Enforce no tabs, only spaces for indent. -->
  <module name="FileTabCharacter">
    <property name="eachLine" value="true"/>
    <property name="severity" value="error"/>
  </module>

  <!-- Enforce Unix newlines. -->
  <module name="NewlineAtEndOfFile">
    <property name="lineSeparator" value="lf"/>
    <property name="severity" value="error"/>
  </module>

  <!-- Check each Java file for violations. -->
  <module name="TreeWalker">

    <!-- Constants (static finals) must be uppercase letters/digits/underscore. -->
    <module name="ConstantName">
      <property name="format" value="^[A-Z][A-Z0-9_]*$"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Duplicate import checking. -->
    <module name="RedundantImport">
      <property name="severity" value="error"/>
    </module>

    <!-- Unused imports checking. -->
    <module name="UnusedImports">
      <property name="severity" value="error"/>
    </module>

    <!-- Method name check. -->
    <module name="MethodName">
      <property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Local variable name check. -->
    <module name="LocalVariableName">
      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Local variable name check. -->
    <module name="LocalFinalVariableName">
      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Member name check. -->
    <module name="MemberName">
      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Class name check. -->
    <module name="TypeName">
      <property name="format" value="^[A-Z][a-zA-Z0-9]*$"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Left curly goes on end of line (eol). -->
    <module name="LeftCurly">
      <property name="option" value="eol"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Right curly goes same line as 'else', 'try', and 'catch'. -->
    <module name="RightCurly">
      <property name="option" value="same"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Need braces for all code blocks. -->
    <module name="NeedBraces">
      <property name="allowSingleLineStatement" value="true"/>
      <property name="severity" value="error"/>
    </module>

    <!-- Checks that a token is surrounded by whitespace. -->
    <module name="WhitespaceAround">
      <property name="severity" value="error"/>
    </module>

    <!-- Checks that a token is followed by whitespace. -->
    <module name="WhitespaceAfter">
      <property name="severity" value="error"/>
    </module>

    <!-- Checks the policy on the padding of parentheses. -->
    <module name="ParenPad">
      <property name="severity" value="error"/>
    </module>

    <!-- Fails if there is whitespace around generic '<' '>' characters. -->
    <module name="GenericWhitespace">
      <property name="severity" value="error"/>
    </module>

    <!-- Cyclomatic complexity limit of 8. -->
    <module name="CyclomaticComplexity">
      <property name="max" value="8"/>
      <property name="severity" value="warning"/>
    </module>

    <!-- Checks that long constants are defined with an upper ell. 'l' looks too much like '1'. -->
    <module name="UpperEll">
      <property name="severity" value="error"/>
    </module>

    <!-- Enforce Java array type style. -->
    <module name="ArrayTypeStyle">
      <property name="severity" value="error"/>
    </module>

    <!-- Not enforcing Javadoc checkstyles... for now -->
    <!-- Simple Javadoc style check. -->
    <module name="JavadocStyle">
      <property name="severity" value="ignore"/>
    </module>

    <!-- Checks Javadoc comments for class and interface definitions. -->
    <module name="JavadocType">
      <property name="scope" value="protected"/>
      <property name="severity" value="ignore"/>
    </module>

    <!-- Checks the Javadoc of a method or constructor. -->
    <module name="JavadocMethod">
      <property name="scope" value="protected"/>
      <property name="allowThrowsTagsForSubclasses" value="true"/>
      <property name="allowUndeclaredRTE" value="true"/>
      <property name="severity" value="ignore"/>
    </module>

    <!-- Checks that variables have Javadoc comments. -->
    <module name="JavadocVariable">
      <property name="scope" value="protected"/>
      <property name="severity" value="ignore"/>
    </module>

    <!-- Checks if a line it too long. -->
    <module name="LineLength">
      <property name="max" value="120"/>
      <property name="severity" value="ignore"/>
    </module>

    <!-- Checks that there are no import statements that use the * notation.  -->
    <module name="AvoidStarImport"/>
  </module>

</module>