checkstyle.xml

<?xml version="1.0"?>
<!--
  Copyright 2020 Expedia, Inc.

  Licensed 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
    "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
    <module name="FileTabCharacter"/>
    <module name="RegexpMultiline">
        <!-- match any call to org.hamcrest.CoreMatchers, ignoring whitespace -->
        <property name="format" value="\borg\s*\.\s*hamcrest\s*\.\s*CoreMatchers\b"/>
        <property name="maximum" value="0" />
        <property name="message" value="Use org.hamcrest.Matchers (from hamcrest-library) instead of org.hamcrest.CoreMatchers (from hamcrest-core)."/>
    </module>
    <module name="TreeWalker">
        <property name="tabWidth" value="4"/>
        <!-- Requires unused imports to be cleaned up -->
        <module name="UnusedImports">
            <property name="processJavadoc" value="true"/>
        </module>
        <module name="AvoidStarImport"/>
        <!-- Enforce Import Order -->
        <module name="ImportOrder">
            <property name="groups" value="/^java\./,/^javax\./,/^org\./,/^com\./"/>
            <property name="staticGroups" value="/^java\./,/^javax\./,/^org\./,/^com\./"/>
            <property name="ordered" value="true"/>
            <property name="separated" value="true"/>
            <property name="separatedStaticGroups" value="true"/>
            <property name="option" value="bottom"/>
            <property name="useContainerOrderingForStatic" value="true"/>
        </module>

        <module name="OneTopLevelClass"/>
        <module name="NoLineWrap"/>
        <module name="EmptyBlock">
            <property name="option" value="TEXT"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
        </module>
        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly"/>
        <module name="GenericWhitespace"/>
        <module name="ParenPad"/>
        <module name="TypecastParenPad"/>
        <module name="WhitespaceAfter"/>
        <module name="WhitespaceAround">
            <property name="allowEmptyConstructors" value="true" />
            <property name="allowEmptyMethods" value="true" />
            <property name="allowEmptyTypes" value="true" />
            <property name="allowEmptyLoops" value="true" />
        </module>
        <module name="OneStatementPerLine"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="ArrayTypeStyle"/>
        <module name="FallThrough"/>
        <module name="UpperEll"/>
        <module name="ModifierOrder"/>
        <module name="EmptyLineSeparator">
            <property name="allowNoEmptyLineBetweenFields" value="true"/>
            <property name="tokens" value="IMPORT, CLASS_DEF, INTERFACE_DEF, ENUM_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="DOT"/>
            <property name="option" value="nl"/>
        </module>
        <module name="SeparatorWrap">
            <property name="tokens" value="COMMA"/>
            <property name="option" value="EOL"/>
        </module>
        <module name="PackageName">
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
            <message key="name.invalidPattern"
                     value="Package name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="TypeName">
            <message key="name.invalidPattern"
                     value="Type name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="MemberName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
            <message key="name.invalidPattern"
                     value="Member name ''{0}'' must match pattern ''{1}''."/>
        </module>
        <module name="NoFinalizer"/>
        <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="MissingOverride"/>

        <module name="SuppressWithNearbyCommentFilter">
            <property name="commentFormat" value="CHECKSTYLE IGNORE (\w+) FOR NEXT (\d+) LINES"/>
            <property name="checkFormat" value="$1"/>
            <property name="influenceFormat" value="$2"/>
        </module>
    </module>
</module>