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">

    <module name="LineLength">
        <property name="severity" value="warning"/>
        <property name="fileExtensions" value="java"/>
        <property name="max" value="100"/>
        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
    </module>

    <!-- Filter out Checkstyle warnings that have been suppressed with the @SuppressWarnings annotation -->
    <module name="SuppressWarningsFilter" />

    <module name="TreeWalker">
        <!-- Make the @SuppressWarnings annotations available to Checkstyle -->
        <module name="SuppressWarningsHolder" />

        <module name="CyclomaticComplexity">
            <property name="severity" value="warning"/>
            <property name="switchBlockAsSingleDecisionPoint" value="true"/>
            <property name="max" value="6"/>
        </module>

        <module name="Indentation">
            <property name="severity" value="warning"/>
        </module>

        <module name="UnusedImports">
            <property name="severity" value="warning"/>
        </module>

        <module name="MethodLength">
            <property name="severity" value="warning"/>
            <property name="tokens" value="METHOD_DEF, CTOR_DEF, COMPACT_CTOR_DEF"/>
            <property name="max" value="50"/>
        </module>

        <module name="CommentsIndentation">
            <property name="severity" value="warning"/>
        </module>

        <module name="SingleSpaceSeparator">
            <property name="severity" value="warning"/>
            <property name="validateComments" value="true"/>
        </module>

        <module name="NeedBraces">
            <property name="severity" value="warning"/>
            <property name="tokens" value="LITERAL_CASE, LITERAL_DEFAULT"/>
            <property name="allowSingleLineStatement" value="true"/>
        </module>

        <module name="StringLiteralEquality">
            <property name="severity" value="warning"/>
        </module>

        <module name="SimplifyBooleanReturn">
            <property name="severity" value="warning"/>
        </module>

        <module name="EqualsHashCode">
            <property name="severity" value="warning"/>
        </module>

        <module name="RightCurly">
            <property name="option" value="alone_or_singleline"/>
            <property name="tokens" value="LITERAL_IF, METHOD_DEF, LITERAL_TRY"/>
        </module>

        <module name="ConstantName">
            <property name="format"
                      value="^log(ger)?$|^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$"/>
        </module>

        <module name="LeftCurly">
            <property name="severity" value="warning"/>
        </module>

    </module>

</module>