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="fileExtensions" value="java, xml, properties"/>
    <property name="severity"
              value="warning"/><!-- TODO: Replace with 'error' when problems will be fixed -->
    <property name="haltOnException" value="false"/>

    <module name="FileLength"><!-- Checks for Java file Size Violations -->
        <property name="max" value="3500"/>
        <property name="fileExtensions" value="java"/>
    </module>

    <module name="FileTabCharacter"><!-- Checks for whitespace (Not tabs accepted). Report for each line -->
        <property name="eachLine" value="true"/>
    </module>

    <module name="TreeWalker"><!-- Check source files -->
        <module name="AvoidStarImport"/><!-- No *-import accepted -->

        <module name="OuterTypeFilename"/><!-- Outer type name matches filename -->
        <module name="StaticVariableName"><!-- Static variables (non-final) match lower camel case -->
            <property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/>
        </module>
        <module name="ConstantName"><!-- Static constants (final) match upper case (except serialVersionUID) -->
            <property name="format" value="^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$"/>
        </module>
        <module name="TypeName"><!-- Type names for classes, interfaces, enums and annotations -->
            <property name="format" value="^[A-Z][a-zA-Z0-9]*$"/>
        </module>

        <module name="LineLength"><!-- Check line length -->
            <property name="max" value="160"/>
            <property name="ignorePattern"
                      value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
        </module>

        <module name="OneTopLevelClass"/>

        <module name="NoLineWrap"/>
        <module name="NeedBraces"/>
        <module name="LeftCurly"/>
        <module name="RightCurly">
            <property name="id" value="RightCurlySame"/>
            <property name="tokens"
                      value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_DO"/>
        </module>
        <module name="RightCurly">
            <property name="id" value="RightCurlyAlone"/>
            <property name="option" value="alone"/>
            <property name="tokens"
                      value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT"/>
        </module>
        <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="ModifierOrder"/>
    </module>
</module>