checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
    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
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<!-- This is a checkstyle configuration file. For descriptions of
what the following rules do, please see the checkstyle configuration
page at http://checkstyle.sourceforge.net/config.html -->

<module name="Checker">

    <!-- Prevent *Tests.java as tools may not pick them up -->
    <module name="RegexpOnFilename">
        <property name="fileNamePattern" value=".*Tests\.java$" />
    </module>

    <module name="SuppressionFilter">
        <property name="file" value="${checkstyle.suppressions.file}" default="suppressions.xml" />
    </module>

    <!-- All Java AST specific tests live under TreeWalker module. -->
    <module name="TreeWalker">

        <!-- Allow use of comment to suppress javadocstyle -->
        <module name="SuppressionCommentFilter">
            <property name="offCommentFormat" value="CHECKSTYLE.OFF\: ([\w\|]+)"/>
            <property name="onCommentFormat" value="CHECKSTYLE.ON\: ([\w\|]+)"/>
            <property name="checkFormat" value="$1"/>
        </module>
        <module name="TodoComment">
            <!-- Checks that disallowed strings are not used in comments.  -->
            <property name="format" value="(@author)" />
        </module>


        <module name="PackageName">
            <!-- Validates identifiers for package names against the
            supplied expression. -->
            <!-- Here the default checkstyle rule restricts package name parts to
              seven characters, this is not in line with common practice at Google.
            -->
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
            <property name="severity" value="error"/>
        </module>

    </module>
</module>