config/checkstyle/checkstyle.xml

<?xml version="1.0"?>
<!--
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License 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
          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
          "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">

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

    <property name="fileExtensions" value="java, xml, properties, gradle, sh" />

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

    <!-- https://checkstyle.org/config_filters.html#SuppressionFilter -->
    <module name="SuppressionFilter">
        <property name="file" value="${config_loc}/suppressions.xml" />
        <property name="optional" value="false" />
    </module>

    <!-- Checks that a 'package-info.java' file exists for each package. -->
    <!-- See https://checkstyle.org/config_javadoc.html#JavadocPackage   -->
    <module name="JavadocPackage" />

    <!-- Checks for the presence of Apache license headers.   -->
    <!-- See https://checkstyle.org/config_header.html        -->
    <module name="RegexpHeader">
        <property name="fileExtensions" value="java" />
        <property name="header" value="^/\*\n \* Licensed to the Apache Software Foundation" />
    </module>
    <!-- TODO: Add checks for other file types (xml, properties, gradle, sh) -->

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

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

    <!-- Checks for size violations.                  -->
    <!-- See https://checkstyle.org/config_sizes.html -->
    <module name="FileLength">
        <property name="fileExtensions" value="java, xml, properties, gradle, sh" />
        <property name="max" value="3500" />
    </module>
    <module name="LineLength">
        <property name="fileExtensions" value="java, xml, properties, gradle, sh" />
        <property name="ignorePattern" value="\b(package|import|Pattern\.compile|https?:://|CHECKSTYLE IGNORE)\b"/>
        <property name="max" value="160" />
    </module>

    <!-- Checks for whitespace.                            -->
    <!-- See https://checkstyle.org/config_whitespace.html -->
    <module name="FileTabCharacter" />

    <!-- Miscellaneous other checks.                 -->
    <!-- See https://checkstyle.org/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="TreeWalker">

        <property name="tabWidth" value="4"/>

        <!-- Enables in-code single-line suppressions with a comment.                       -->
        <!-- See https://checkstyle.org/config_filters.html#SuppressWithNearbyCommentFilter -->
        <module name="SuppressWithNearbyCommentFilter">
            <property name="commentFormat" value="CHECKSTYLE\s+IGNORE:\s+\S+" />
            <property name="influenceFormat" value="-1" />
        </module>
        <module name="SuppressWithNearbyCommentFilter">
            <property name="commentFormat" value="CHECKSTYLE\s+IGNORE:\s+\S+" />
            <property name="influenceFormat" value="+1" />
        </module>

        <!-- Checks for JavaDoc comments.                   -->
        <!-- See https://checkstyle.org/config_javadoc.html -->
        <module name="InvalidJavadocPosition" />
        <module name="JavadocMethod" />
        <module name="JavadocType" />
        <module name="JavadocVariable" />
        <module name="JavadocStyle">
            <property name="checkFirstSentence" value="false" />
        </module>
        <module name="MissingJavadocMethod" />

        <!-- Checks for naming conventions.                -->
        <!-- See https://checkstyle.org/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 https://checkstyle.org/config_imports.html -->
        <module name="AvoidStarImport" />
        <module name="IllegalImport" />
        <module name="RedundantImport" />
        <module name="UnusedImports" />

        <!-- Checks for size violations.                  -->
        <!-- See https://checkstyle.org/config_sizes.html -->
        <module name="MethodLength">
            <property name="max" value="120" />
        </module>
        <module name="ParameterNumber">
            <property name="max" value="8" />
            <property name="ignoreOverriddenMethods" value="true" />
        </module>

        <!-- Checks for whitespace.                            -->
        <!-- See https://checkstyle.org/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 https://checkstyle.org/config_modifier.html -->
        <module name="ModifierOrder" />
        <module name="RedundantModifier" />

        <!-- Checks for blocks. You know, those {}'s.      -->
        <!-- See https://checkstyle.org/config_blocks.html -->
        <module name="AvoidNestedBlocks" />
        <module name="EmptyBlock" />
        <module name="LeftCurly">
            <property name="option" value="eol" />
            <property name="tokens" value="LAMBDA" />
        </module>
        <module name="LeftCurly">
            <property name="option" value="nl" />
            <property name="ignoreEnums" value="false" />
            <property name="tokens" value="ANNOTATION_DEF, CLASS_DEF, CTOR_DEF, ENUM_CONSTANT_DEF, ENUM_DEF,
                                           INTERFACE_DEF, LITERAL_CASE, LITERAL_CATCH, LITERAL_DEFAULT,
                                           LITERAL_DO, LITERAL_ELSE, LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF,
                                           LITERAL_SWITCH, LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE,
                                           METHOD_DEF, OBJBLOCK, STATIC_INIT, RECORD_DEF, COMPACT_CTOR_DEF" />
        </module>
        <module name="NeedBraces" />
        <module name="RightCurly">
            <property name="option" value="alone" />
        </module>

        <!-- Checks for common coding problems.            -->
        <!-- See https://checkstyle.org/config_coding.html -->
        <module name="EmptyStatement" />
        <module name="EqualsHashCode" />
        <module name="HiddenField">
            <property name="ignoreConstructorParameter" value="true" />
            <property name="ignoreSetter" value="true" />
        </module>
        <module name="IllegalInstantiation" />
        <module name="InnerAssignment" />
        <module name="MagicNumber">
            <property name="ignoreNumbers" value="-2147483648, -32768, -128, -1, 0, 1, 2, 3, 4, 8, 16, 32,
                                                  42, 64, 127, 128, 255, 256, 512, 1000, 1024, 2048, 4096, 8192,
                                                  16384, 32767, 32768, 65535, 65536, 1000000, 1048576, 1000000000,
                                                  1073741824, 2147483647, 2147483648, 4294967295" />
        </module>
        <module name="MissingSwitchDefault" />
        <module name="MultipleVariableDeclarations" />
        <module name="SimplifyBooleanExpression" />
        <module name="SimplifyBooleanReturn" />

        <!-- Checks for class design.                      -->
        <!-- See https://checkstyle.org/config_design.html -->
        <module name="DesignForExtension" />
<!--        <module name="FinalClass" />-->
        <module name="HideUtilityClassConstructor" />
        <module name="InterfaceIsType" />
        <!-- Miscellaneous other checks.                 -->
        <!-- See https://checkstyle.org/config_misc.html -->
        <module name="ArrayTypeStyle" />
        <module name="TodoComment" />
        <module name="UpperEll" />

    </module>

</module>