checkstyle.xml

<?xml version="1.0"?>
<!--
 Copyright 2020 Google LLC

 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

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 distributed under the License is distributed on an "AS IS" BASIS,
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 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">

<!--

  Checkstyle configuration that checks the sun coding conventions from:

    - the Java Language Specification at
      http://java.sun.com/docs/books/jls/second_edition/html/index.html

    - the Sun Code Conventions at http://java.sun.com/docs/codeconv/

    - the Javadoc guidelines at
      http://java.sun.com/j2se/javadoc/writingdoccomments/index.html

    - the JDK Api documentation http://java.sun.com/j2se/docs/api/index.html

    - some best practices

  Checkstyle is very configurable. Be sure to read the documentation at
  http://checkstyle.sf.net (or in your downloaded distribution).

  Most Checks are configurable, be sure to consult the documentation.

  To completely disable a check, just comment it out or delete it from the file.

  Finally, it is worth reading the documentation.

-->

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

    <!--
        If you set the basedir property below, then all reported file
        names will be relative to the specified directory. See
        http://checkstyle.sourceforge.net/5.x/config.html#Checker

        <property name="basedir" value="${basedir}"/>
    -->

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

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

    <module name="FileLength"/>

    <!-- Following interprets the header file as regular expressions. -->
    <!-- <module name="RegexpHeader"/>                                -->

    <module name="FileTabCharacter">
        <property name="eachLine" value="true"/>
    </module>

    <module name="RegexpSingleline">
        <!-- \s matches whitespace character, $ matches end of line. -->
        <property name="format" value="\s+$"/>
        <property name="message" value="Line has trailing spaces."/>
    </module>

    <module name="LineLength">
        <property name="severity" value="warning"/>
        <property name="fileExtensions" value="java"/>
        <property name="max" value="120"/>
        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
    </module>

    <module name="TreeWalker">
        <!-- required for SuppressWarningsFilter (and other Suppress* rules not used here) -->
        <!-- see http://checkstyle.sourceforge.net/config_annotation.html#SuppressWarningsHolder -->
        <module name="SuppressWarningsHolder"/>


        <!-- Checks for Naming Conventions.                  -->
        <!-- See http://checkstyle.sf.net/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 Headers                                -->
        <!-- See http://checkstyle.sf.net/config_header.html   -->
        <!-- <module name="Header">                            -->
        <!-- The follow property value demonstrates the ability     -->
        <!-- to have access to ANT properties. In this case it uses -->
        <!-- the ${basedir} property to allow Checkstyle to be run  -->
        <!-- from any directory within a project. See property      -->
        <!-- expansion,                                             -->
        <!-- http://checkstyle.sf.net/config.html#properties        -->
        <!-- <property                                              -->
        <!--     name="headerFile"                                  -->
        <!--     value="${basedir}/java.header"/>                   -->
        <!-- </module> -->


        <!-- Checks for imports                              -->
        <!-- See http://checkstyle.sf.net/config_import.html -->
        <module name="AvoidStarImport"/>
        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
        <module name="RedundantImport"/>
        <module name="UnusedImports"/>


        <!-- Checks for Size Violations.                    -->
        <!-- See http://checkstyle.sf.net/config_sizes.html -->
        <module name="MethodLength"/>
        <module name="ParameterNumber"/>


        <!-- Checks for whitespace                               -->
        <!-- See http://checkstyle.sf.net/config_whitespace.html -->
        <module name="EmptyForIteratorPad"/>
        <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 http://checkstyle.sf.net/config_modifiers.html -->
        <module name="ModifierOrder"/>
        <module name="RedundantModifier"/>


        <!-- Checks for blocks. You know, those {}'s         -->
        <!-- See http://checkstyle.sf.net/config_blocks.html -->
        <module name="AvoidNestedBlocks"/>
        <module name="EmptyBlock"/>
        <module name="LeftCurly"/>
        <module name="NeedBraces"/>
        <module name="RightCurly"/>


        <!-- Checks for common coding problems               -->
        <!-- See http://checkstyle.sf.net/config_coding.html -->
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <module name="IllegalInstantiation"/>
        <module name="InnerAssignment"/>
        <module name="MagicNumber"/>
        <module name="MissingSwitchDefault"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>

        <!-- Checks for class design                         -->
        <!-- See http://checkstyle.sf.net/config_design.html -->
        <module name="FinalClass"/>
        <module name="InterfaceIsType"/>
        <!--<module name="VisibilityModifier"/>-->


        <!-- Miscellaneous other checks.                   -->
        <!-- See http://checkstyle.sf.net/config_misc.html -->
        <module name="ArrayTypeStyle"/>
        <module name="UpperEll"/>

    </module>

    <!-- Support @SuppressWarnings (added in Checkstyle 5.7) -->
    <!-- see http://checkstyle.sourceforge.net/config.html#SuppressWarningsFilter -->
    <module name="SuppressWarningsFilter"/>

    <!-- Checks properties file for a duplicated properties. -->
    <!-- See http://checkstyle.sourceforge.net/config_misc.html#UniqueProperties -->
    <module name="UniqueProperties"/>

</module>