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">
  <property name="charset" value="UTF-8"/>

  <property name="severity" value="error"/>

  <property name="fileExtensions" value="java, properties, xml"/>
  <module name="BeforeExecutionExclusionFileFilter">
    <property name="fileNamePattern" value="module\-info\.java$"/>
  </module>

  <module name="TreeWalker">
    <module name="OuterTypeFilename"/>
    <module name="NoLineWrap">
      <property name="tokens" value="PACKAGE_DEF, IMPORT, STATIC_IMPORT"/>
    </module>
    <module name="LeftCurly" />
    <module name="RightCurly" />
    <module name="WhitespaceAfter"/>
    <module name="WhitespaceAround">
      <property name="allowEmptyConstructors" value="true"/>
      <property name="allowEmptyLambdas" value="true"/>
      <property name="allowEmptyMethods" value="true"/>
      <property name="allowEmptyTypes" value="true"/>
      <property name="allowEmptyLoops" value="true"/>
      <property name="allowEmptyCatches" value="true"/>
      <property name="ignoreEnhancedForColon" value="false"/>
      <property name="tokens"
                value="ASSIGN, BAND, BAND_ASSIGN, BOR, BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR,
                    BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN, DO_WHILE, EQUAL, GE, GT, LAMBDA, LAND,
                    LCURLY, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE, LITERAL_FINALLY,
                    LITERAL_FOR, LITERAL_IF, LITERAL_RETURN, LITERAL_SWITCH, LITERAL_SYNCHRONIZED,
                    LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS, MINUS_ASSIGN, MOD, MOD_ASSIGN,
                    NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION, RCURLY, SL, SLIST, SL_ASSIGN, SR,
                    SR_ASSIGN, STAR, STAR_ASSIGN, LITERAL_ASSERT, TYPE_EXTENSION_AND"/>
      <message key="ws.notFollowed"
               value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
      <message key="ws.notPreceded"
               value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
    </module>
    <module name="GenericWhitespace">
      <message key="ws.followed"
               value="GenericWhitespace ''{0}'' is followed by whitespace."/>
      <message key="ws.preceded"
               value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
      <message key="ws.illegalFollow"
               value="GenericWhitespace ''{0}'' should followed by whitespace."/>
      <message key="ws.notPreceded"
               value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
    </module>
    <module name="OneStatementPerLine"/>
    <module name="ModifierOrder"/>
    <module name="EmptyLineSeparator">
      <property name="tokens"
                value="PACKAGE_DEF, IMPORT, STATIC_IMPORT, CLASS_DEF, INTERFACE_DEF, ENUM_DEF,
                    STATIC_INIT, INSTANCE_INIT, CTOR_DEF, VARIABLE_DEF"/>
      <property name="allowNoEmptyLineBetweenFields" value="true"/>
    </module>
    <module name="SeparatorWrap">
      <property name="id" value="SeparatorWrapDot"/>
      <property name="tokens" value="DOT"/>
      <property name="option" value="nl"/>
    </module>
    <module name="SeparatorWrap">
      <property name="id" value="SeparatorWrapComma"/>
      <property name="tokens" value="COMMA"/>
      <property name="option" value="EOL"/>
    </module>

    <module name="CustomImportOrder">
      <property name="sortImportsInGroupAlphabetically" value="true"/>
      <property name="separateLineBetweenGroups" value="true"/>
      <property name="customImportOrderRules" value="STATIC###THIRD_PARTY_PACKAGE"/>
      <property name="tokens" value="IMPORT, STATIC_IMPORT, PACKAGE_DEF"/>
    </module>
    <module name="MethodParamPad">
      <property name="tokens"
                value="CTOR_DEF, LITERAL_NEW, METHOD_CALL, METHOD_DEF,
                    SUPER_CTOR_CALL, ENUM_CONSTANT_DEF"/>
    </module>
    <module name="NoWhitespaceBefore">
      <property name="tokens"
                value="COMMA, SEMI, POST_INC, POST_DEC, DOT,
                    LABELED_STAT, METHOD_REF"/>
      <property name="allowLineBreaks" value="true"/>
    </module>
    <module name="ParenPad"/>
    <module name="AnnotationLocation">
      <property name="allowSamelineMultipleAnnotations" value="false"/>
      <property name="allowSamelineSingleParameterlessAnnotation" value="false"/>
      <property name="allowSamelineParameterizedAnnotation" value="false"/>
    </module>
  </module>
</module>