Google Git
Sign in
android / platform / external / checkstyle / 70fd1618553f9bff32c4cfc39754ea3c2e99fc88 / . / src / xdocs / config.xml
blob: 1b71431604249e8f5229d02766ad96551ca38a97 [file] [log] [blame]
<?xml version="1.0" encoding="UTF-8"?>
<document xmlns="http://maven.apache.org/XDOC/2.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 http://maven.apache.org/xsd/xdoc-2.0.xsd">
<head>
<title>Configuration</title>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"/>
<script type="text/javascript" src="js/anchors.js"/>
<script type="text/javascript" src="js/google-analytics.js"/>
<link rel="icon" href="images/favicon.png" type="image/x-icon" />
<link rel="shortcut icon" href="images/favicon.ico" type="image/ico" />
</head>
<body>
<section name="Content">
<macro name="toc">
<param name="fromDepth" value="1"/>
<param name="toDepth" value="1"/>
</macro>
</section>
<section name="Overview">
<p>
A Checkstyle configuration specifies which <em>modules</em> to
plug in and apply to Java source files. Modules are structured
in a tree whose root is the <em>Checker</em> module. The next
level of modules contains:
</p>
<ul>
<li><em>FileSetChecks</em> - modules that take a set of input
files and fire error messages.</li>
<li><em>Filters</em>
- modules that filter audit events,
including error messages, for acceptance.</li>
<li><em>AuditListeners</em> - modules that report accepted events.</li>
</ul>
<p>
Many checks are submodules of the <em>TreeWalker</em>
FileSetCheck module. The TreeWalker operates by separately
transforming each of the Java source files into an abstract
syntax tree and then handing the result over to each of its
submodules which in turn have a look at certain aspects of the
tree.
</p>
<p>
Checkstyle obtains a configuration from an XML document whose
elements specify the configuration's hierarchy of modules and
their properties. You provide a file that contains the
configuration document when you invoke Checkstyle at the <a
href="cmdline.html">command line</a>, and when you run a <a
href="anttask.html">Checkstyle task</a> in ant. The
documentation directory of the Checkstyle distribution contains
a sample configuration file <em>sun_checks.xml</em> which
configures Checkstyle to check for the Sun coding conventions.
</p>
</section>
<section name="Modules">
<p>
A <code>module</code> element in the configuration
XML document specifies a module identified by the element's
<code>name</code> attribute.
</p>
<p>
Here is a fragment of a typical configuration document:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;module name=&quot;JavadocPackage&quot;/&gt;
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;module name=&quot;AvoidStarImport&quot;/&gt;
&lt;module name=&quot;ConstantName&quot;/&gt;
&lt;module name=&quot;EmptyBlock&quot;/&gt;
&lt;/module&gt;
&lt;/module&gt;
</source>
<p>
In this configuration:
</p>
<ul>
<li>
Root module <code>Checker</code> has child
FileSetChecks <code>JavadocPackage</code> and <code>TreeWalker</code>. (Module <a
href="config_javadoc.html"> <code>JavadocPackage</code></a> checks that all packages
have package documentation.)
</li>
<li>
Module <code>TreeWalker</code> has submodules
<code>AvoidStarImport</code>, <code>ConstantName</code>, and <code>EmptyBlock</code>. (Modules <a
href="config_imports.html"><code>AvoidStarImport</code></a>, <a
href="config_naming.html"><code>ConstantName</code></a>, and <a
href="config_blocks.html"><code>EmptyBlock</code></a> check that a Java source
file has no star imports, has valid constant names, and has no
empty blocks, respectively.)
</li>
</ul>
<p>
For each configuration module, Checkstyle loads a class
identified by the <code>name</code> attribute of
the <code>module</code>. There are several rules
for loading a module's class:
</p>
<ol>
<li>
Load a class directly according to a package-qualified <code>name</code>, such as loading class <code>com.puppycrawl.tools.checkstyle.TreeWalker</code>
for element:
<source>
&lt;module name=&quot;com.puppycrawl.tools.checkstyle.TreeWalker&quot;/&gt;
</source>
This is useful for plugging third-party modules into a configuration.
</li>
<li>
Load a class of a pre-specified package, such as loading class
<code>com.puppycrawl.tools.checkstyle.checks.AvoidStarImport</code>
for element
<source>
&lt;module name=&quot;AvoidStarImport&quot;/&gt;
</source>
Checkstyle applies packages <code>
com.puppycrawl.tools.checkstyle</code>, <code>
com.puppycrawl.tools.checkstyle.filters</code>, and <code> com.puppycrawl.tools.checkstyle.checks</code>
and its sub-packages (only those included in the Checkstyle
distribution). You can specify other packages in a <a
href="#Packages"><em>package names XML document</em></a>
when you invoke Checkstyle at the <a
href="cmdline.html">command line</a>, and when you run a <a
href="anttask.html">Checkstyle task</a> in ant.
</li>
<li>
Apply the above rules to <code>name</code>
concatenated with <code>&quot;Check&quot;</code>,
such as loading class <code>com.puppycrawl.tools.checkstyle.checks.ConstantNameCheck</code>
for element
<source>
&lt;module name=&quot;ConstantName&quot;/&gt;
</source>
</li>
</ol>
</section>
<section name="Properties">
<p>
Properties of a module control how the module performs its task.
Each module property has a default value, and you are not
required to define a property in the configuration document if
the default value is satisfactory. To assign a non-default
value to a module's property, define a child <code>property</code> element of the <code>module</code> element in the configuration XML
document. Also provide appropriate <code>name</code> and <code>value</code>
attributes for the <code>property</code> element.
For example, property <code>max</code> of module
<code>MethodLength</code> specifies the maximum
allowable number of lines in a method or constructor, and has
default value <code>150</code>. Here is a
configuration of module <code>MethodLength</code>
so that the check reports methods and constructors with more
than <code>60</code> lines:
</p>
<source>
&lt;module name=&quot;MethodLength&quot;&gt;
&lt;property name=&quot;max&quot; value=&quot;60&quot;/&gt;
&lt;/module&gt;
</source>
<p>
<a href="cmdline.html">Command line</a> properties and ant <a
href="anttask.html">Checkstyle task</a> properties apply to the
root <code>Checker</code> module. Also, properties
are inherited in the module hierarchy. These features make it
easy to define one property value that applies to many
modules. For example, the following configuration fragment
specifies that a <code>tabWidth</code> of <code>4</code> applies to <code>TreeWalker</code> and its submodules:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;module name=&quot;JavadocPackage&quot;/&gt;
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;property name=&quot;tabWidth&quot; value=&quot;4&quot;/&gt;
&lt;module name=&quot;AvoidStarImport&quot;/&gt;
&lt;module name=&quot;ConstantName&quot;/&gt;
...
&lt;/module&gt;
&lt;/module&gt;
</source>
<p>
The value of a module property can be specified through
<em>property expansion</em> with the <code>${<em>property_name</em>}</code> notation, where
<code><em>property_name</em></code> is a <a
href="cmdline.html">command line</a> property or an ant <a
href="anttask.html">Checkstyle task</a> property. For example,
the following configuration document element gives property
<code>headerFile</code> the value of command line
property <code>checkstyle.header.file</code>:
</p>
<source>
&lt;module name=&quot;Header&quot;&gt;
&lt;property name=&quot;headerFile&quot; value=&quot;${checkstyle.header.file}&quot;/&gt;
&lt;/module&gt;
</source>
<p>
You can use property expansion to re-specify a module property
value without changing the configuration document.
</p>
<p>
The property element provides an optional <code>default</code> attribute which is used when a
property in the value cannot be resolved. For example this
configuration snippet from a central configuration file checks
that methods have javadoc, but allows individual projects to
override the severity by specifying their desired value in the
command line property <code>checkstyle.javadoc.severity</code>:
</p>
<source>
&lt;module name=&quot;JavadocMethod&quot;&gt;
&lt;property name=&quot;severity&quot;
value=&quot;${checkstyle.javadoc.severity}&quot;
default=&quot;error&quot;/&gt;
&lt;/module&gt;
</source>
<p>
This feature is a great help when setting up a centralized
configuration file (e.g. one file for the whole company) to
lower configuration maintenance costs. Projects that are happy
with the default can simply use that configuration file as is,
but individual projects with special needs have the flexibility
to adjust a few settings to fit their needs without having to
copy and maintain the whole configuration.
</p>
<p>
You can find information about property types on
<a href="property_types.html">Property Types</a> page.
</p>
</section>
<section name="Checker">
<subsection name="Description">
<p>Since Checkstyle 3.0</p>
<p>
All configurations have root module <code>Checker</code>. <code>Checker</code>
contains:
</p>
<ul>
<li><em>FileSetCheck</em> children: modules that check sets of
files.</li>
<li><em>Filter</em> children: modules that filter audit
events.</li>
<li><em>FileFilter</em> children: modules that filter files
for Checkstyle to process.</li>
<li><em>AuditListener</em> children: modules that report
filtered events.</li>
</ul>
<p>
<code>Checker</code> also defines properties that are
inherited by all other modules of a configuration.
</p>
</subsection>
<subsection name="Properties">
<table>
<tr>
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
<th>since</th>
</tr>
<tr>
<td>basedir</td>
<td>base directory name; stripped off in messages about files</td>
<td><a href="property_types.html#string">string</a></td>
<td><code>null</code></td>
<td>3.0</td>
</tr>
<tr>
<td>cacheFile</td>
<td>caches information about files that have checked OK; used
to avoid repeated checks of the same files</td>
<td><a href="property_types.html#string">string</a></td>
<td><code>null</code> (no cache file)</td>
<td>6.16</td>
</tr>
<tr>
<td>localeCountry</td>
<td>locale country for messages</td>
<td><a href="property_types.html#string">string</a>: either
the empty string or an uppercase ISO 3166 2-letter code</td>
<td>default locale country for the Java Virtual Machine</td>
<td>3.0</td>
</tr>
<tr>
<td>localeLanguage</td>
<td>locale language for messages</td>
<td><a href="property_types.html#string">string</a>: either
the empty string or a lowercase ISO 639 code</td>
<td>default locale language for the Java Virtual Machine</td>
<td>3.0</td>
</tr>
<tr>
<td>charset</td>
<td>name of the file charset</td>
<td><a href="property_types.html#string">String</a></td>
<td>System property &quot;file.encoding&quot;</td>
<td>5.0</td>
</tr>
<tr>
<td>fileExtensions</td>
<td>file extensions that are accepted</td>
<td><a href="property_types.html#stringSet">String Set</a></td>
<td><code>null</code></td>
<td>6.3</td>
</tr>
<tr>
<td>severity</td>
<td>the default severity level of all violations</td>
<td><a href="property_types.html#severity">Severity</a></td>
<td><code>error</code></td>
<td>3.1</td>
</tr>
<tr>
<td>haltOnException</td>
<td>whether to stop execution of Checkstyle if a single file produces any kind of
exception during verification</td>
<td><a href="property_types.html#boolean">Boolean</a></td>
<td><code>true</code></td>
<td>7.4</td>
</tr>
</table>
</subsection>
<subsection name="Examples">
<p>
For example, the following configuration fragment specifies base
directory <code>src/checkstyle</code>, cache file <code>target/cachefile</code> and German
locale for all modules:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;property name=&quot;basedir&quot; value=&quot;src/checkstyle&quot;/&gt;
&lt;property name=&quot;cacheFile&quot; value=&quot;target/cachefile&quot;/&gt;
&lt;property name=&quot;localeCountry&quot; value=&quot;DE&quot;/&gt;
&lt;property name=&quot;localeLanguage&quot; value=&quot;de&quot;/&gt;
&lt;module name=&quot;JavadocPackage&quot;/&gt;
&lt;module name=&quot;TreeWalker&quot;&gt;
...
&lt;/module&gt;
&lt;/module&gt;
</source>
<p>
To configure a <code>Checker</code> so that it
handles files with the <code>UTF-8</code> charset:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;property name=&quot;charset&quot; value=&quot;UTF-8&quot;/&gt;
...
&lt;/module&gt;
</source>
<p>
To configure a <code>Checker</code> so that it
handles files with the <code>java, xml, properties</code> extensions:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;java, xml, properties&quot;/&gt;
...
&lt;/module&gt;
</source>
<p>
To configure a <code>Checker</code> so that it doesn't stop execution on an
<code>Exception</code> and instead prints it as a violation:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;property name=&quot;haltOnException&quot; value=&quot;false&quot;/&gt;
...
&lt;/module&gt;
</source>
<p>
To configure a <code>Checker</code> so that it
handles files with any extension:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;null&quot;/&gt;
...
&lt;/module&gt;
</source>
<p>OR</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;&quot;/&gt;
...
&lt;/module&gt;
</source>
</subsection>
</section>
<section name="TreeWalker">
<subsection name="Description">
<p>Since Checkstyle 3.0</p>
<p>
FileSetCheck <code>TreeWalker</code> checks
individual Java source files and defines properties that are
applicable to checking such files.
</p>
</subsection>
<subsection name="Properties">
<table>
<tr>
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
<th>since</th>
</tr>
<tr>
<td>tabWidth</td>
<td>number of expanded spaces for a tab character (<code>'\t'</code>); used in messages and Checks that
require a tab width, such as <a
href="config_sizes.html#LineLength"><code>LineLength</code></a></td>
<td><a href="property_types.html#integer">Integer</a></td>
<td><code>8</code></td>
<td>3.0</td>
</tr>
<tr>
<td>fileExtensions</td>
<td>file type extension to identify Java files. Setting this
property is typically only required if your Java source code
is preprocessed before compilation and the original files do
not have the extension <code>.java</code></td>
<td><a href="property_types.html#stringSet">String Set</a></td>
<td><code>java</code></td>
<td>3.0</td>
</tr>
</table>
</subsection>
<subsection name="Examples">
<p>
For example, the following configuration fragment specifies
<code>TreeWalker</code> a <code>tabWidth</code> of <code>4</code>:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;property name=&quot;tabWidth&quot; value=&quot;4&quot;/&gt;
...
&lt;/module&gt;
&lt;/module&gt;
</source>
<p>
<!--
thanks to Paul King for this example, see
https://sourceforge.net/tracker/?func=detail&aid=865610&group_id=29721&atid=397078
-->
To integrate Checkstyle with BEA Weblogic Workshop 8.1:
</p>
<source>
&lt;module name=&quot;Checker&quot;&gt;
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;java,ejb,jpf&quot;/&gt;
...
&lt;/module&gt;
&lt;/module&gt;
</source>
<p>
To configure <code>TreeWalker</code> so that it
handles files with the <code>java</code> extension:
</p>
<source>
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;java&quot;/&gt;
...
&lt;/module&gt;
</source>
<p>
To configure <code>TreeWalker</code> so that it
handles files with any extension:
</p>
<source>
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;null&quot;/&gt;
...
&lt;/module&gt;
</source>
<p>OR</p>
<source>
&lt;module name=&quot;TreeWalker&quot;&gt;
&lt;property name=&quot;fileExtensions&quot; value=&quot;&quot;/&gt;
...
&lt;/module&gt;
</source>
</subsection>
</section>
<section name="TreeWalker Checks">
<p>
The <code>TreeWalker</code> module creates a syntax
tree for a Java source file and invokes its submodules, called
<em>Checks</em>, during a walk, or traversal, of the nodes of
the tree. Every node of the syntax tree has a token. A visit to
a node during the traversal triggers all Checks that are
configured for its token. For example, if Check <code>MethodLength</code> has been configured as a
submodule of <code>TreeWalker</code>, then a visit
to a node with a method or a constructor definition token
triggers <code>MethodLength</code> to check the
number of lines of the node's code block.
</p>
<p>
Some Checks, such as <code>FileLength</code> and
<code>LineLength</code>, apply directly to the
source file and do not involve tokens of the syntax tree. Other
Checks are associated with configurable sets of tokens that
trigger the Checks. For example, this element configures Check
<code>MethodLength</code>:
</p>
<source>
&lt;module name=&quot;MethodLength&quot;/&gt;
</source>
<p>
The default token set for <code>MethodLength</code>
is <code>{METHOD_DEF, CTOR_DEF}</code>, method
definition and constructor definition tokens, so <code>TreeWalker</code> invokes <code>MethodLength</code> whenever it visits a node with
a <code>METHOD_DEF</code> or a <code>CTOR_DEF</code> token.
</p>
<p>
You specify the trigger tokens for a Check with property <code>tokens</code>. The value of <code>tokens</code> is a list that denotes a subset of
the Check's tokens, as in the following element that configures
Check <code>MethodLength</code> to check the number
of lines of methods only:
</p>
<source>
&lt;module name=&quot;MethodLength&quot;&gt;
&lt;property name=&quot;tokens&quot; value=&quot;METHOD_DEF&quot;/&gt;
&lt;/module&gt;
</source>
<p>
To apply particular properties to different subsets of tokens
for a Check, repeat the Check. For example, to check that the
length of each method is at most 150 lines (the default value of
<code>MethodLength</code> property <code>max</code>) and the length of each constructor is
at most 60 lines, include the following in the <code>TreeWalker</code> configuration:
</p>
<source>
&lt;module name=&quot;MethodLength&quot;&gt;
&lt;property name=&quot;tokens&quot; value=&quot;METHOD_DEF&quot;/&gt;
&lt;/module&gt;
&lt;module name=&quot;MethodLength&quot;&gt;
&lt;property name=&quot;tokens&quot; value=&quot;CTOR_DEF&quot;/&gt;
&lt;property name=&quot;max&quot; value=&quot;60&quot;/&gt;
&lt;/module&gt;
</source>
<p>
Configurations of the Checks are specified in the pages under <a
href="checks.html">here</a>.
</p>
</section>
<section name="Severity">
<p>
Each check has a <a
href="property_types.html#severity">severity</a> property that a
Checkstyle audit assigns to all violations of the check. The
default severity level of a check is <code>error</code>.
</p>
<p>
You can use the severity property to control the output of the
plain formatter for the <a href="cmdline.html">command line
tool</a> and the <a href="anttask.html">ANT task</a>. The plain
formatter does not report violations with severity level <code>ignore</code>, and notes violations with
severity level <code>warning</code>. For
example, according to the following configuration fragment, the
plain formatter outputs warnings for translation violations:
</p>
<source>
&lt;module name=&quot;Translation&quot;&gt;
&lt;property name=&quot;severity&quot; value=&quot;warning&quot;/&gt;
&lt;/module&gt;
</source>
<p>
The XML formatter reports the severity level of every violation
as an attribute of the violation's <code>error</code> element.
</p>
</section>
<section name="Custom messages">
<p>
As of Checkstyle 5 all checks can be configured to report
custom, configuration specific messages instead of the
Checkstyle default messages. This can be useful in cases where
the check message should reference corresponding sections in a
coding style document or the default is too generic for
developers to understand.
</p>
<p>An example usage is:</p>
<source>
&lt;module name=&quot;MemberName&quot;&gt;
&lt;property name=&quot;format&quot; value=&quot;^m[a-zA-Z0-9]*$&quot;/&gt;
&lt;message key=&quot;name.invalidPattern&quot;
value=&quot;Member ''{0}'' must start with a lowercase ''m'' (checked pattern ''{1}'').&quot;
/&gt;
&lt;/module&gt;
</source>
<p>
Each check configuration element can have zero or more <code>message</code> elements. Every check uses one or
more distinct message keys to log violations. If you want to
customize a certain message you need to specify the message key
in the <code>key</code> attribute of the <code>message</code> element.
</p>
<p>
The <code>value</code> attribute specifies the
custom message pattern, as shown in the example above.
Placeholders used in the default message can also be used in the
custom message. Note that the message pattern must be a valid
<a href="https://docs.oracle.com/javase/8/docs/api/java/text/MessageFormat.html">java.text.MessageFormat</a>
style pattern,
so be careful about curly braces outside a placeholder
definition.
</p>
<p>
The obvious question is how do you know which message keys a
Check uses, so that you can override them? You can examine all
keys in the check's specific <a href="checks.html">configuration
documentation</a>. Each check has a section called 'Error Messages'.
This section lists every key the check uses and links to the default
message used by checkstyle.
</p>
</section>
<section name="Filters">
<p>
A Checker module has a set of Filter submodules to filter audit
events, including the error messages fired by Checks. A Filter
can accept or reject an audit event. If all Filters accept an
audit event, then the Checker reports the event. If any Filter
rejects an event, then the Checker does not report the
event. For more information please visit
<a href="config_filters.html">filters page</a>.
</p>
</section>
<section name="Before Execution File Filters">
<p>
A Checker module has a Before Execution File Filter submodule to filter
files from being processed by the utility. A Before Execution File Filter
can accept or reject a file by its name. If all Before Execution File Filters
accept a file, then Checker will process and validate the file.
If any Before Execution File Filter rejects an file, then Checker skips over
the file and acts like it does not exist.
For more information, please visit the <a href="config_filefilters.html">file filters page</a>.
</p>
</section>
<section name="AuditListeners">
<p>
In addition to an audit reporter for text or XML output, a
Checker can have <a href="writinglisteners.html">custom
AuditListeners</a> that handle audit events. In order to use a
custom listener, add a <code>Checker</code> submodule for the
listener and its properties. For example, to configure a <code>Checker</code> so that it uses custom listener <a
href="writinglisteners.html#Writing_Listeners">VerboseListener</a> to
print audit messages to a file named &quot;audit.txt&quot;,
include the following module in the configuration file:
</p>
<source>
&lt;module name=&quot;com.mycompany.listeners.VerboseListener&quot;&gt;
&lt;property name=&quot;file&quot; value=&quot;audit.txt&quot;/&gt;
&lt;/module&gt;
</source>
</section>
<section name="Packages">
<p>
Checkstyle loads a module class according to the <code>name</code> of a <code>module</code>
element, and automatically appends pre-specified package
prefixes to that <code>name</code> in its search
for a loadable class. By default, Checkstyle applies packages
<code> com.puppycrawl.tools.checkstyle</code>,
<code>
com.puppycrawl.tools.checkstyle.filters</code>, and <code> com.puppycrawl.tools.checkstyle.checks</code> as
well as any sub-packages of <code>com.puppycrawl.tools.checkstyle.checks</code> that
are distributed with Checkstyle. However standard checkstyle modules are loaded
with the help of inner map of their names to fully qualified names.
</p>
<p>
To specify other packages to apply,
create a <em>package names XML document</em> in a file
named <code>checkstyle_packages.xml</code>,
and provide that file in the root of the .jar containing your
custom checks.
</p>
<p>
Note that the support for providing a <em>package names XML document</em>
via <a href="cmdline.html">command line</a> option or as a attribute
of an <a href="anttask.html">ant Checkstyle task</a> has been dropped
with Checkstyle 5.0.
</p>
<p>
A <em>package names XML document</em> specifies a list of
package names. Here is a sample package names XML document for
packages <code>
com.puppycrawl.tools.checkstyle</code> and <code>
com.puppycrawl.tools.checkstyle.checks</code>:
</p>
<source>
&lt;checkstyle-packages&gt;
&lt;package name=&quot;com.puppycrawl.tools.checkstyle&quot;&gt;
&lt;package name=&quot;checks&quot;/&gt;
&lt;/package&gt;
&lt;/checkstyle-packages&gt;
</source>
<p>
Notice that the packages are specified recursively - a child
<code>package</code> element is a subpackage of its
parent <code>package</code> element.
</p>
<p>
For example, to incorporate modules from package <code>com.mycompany.checks</code> with Checkstyle
modules, create the XML file below and put this file into the
<b>root of the jar</b> file which contains your custom check modules.
The XML file must be named exactly <code>checkstyle_packages.xml</code>:
</p>
<source>
&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;!DOCTYPE checkstyle-packages PUBLIC
&quot;-//Puppy Crawl//DTD Package Names 1.0//EN&quot;
&quot;http://checkstyle.sourceforge.net/dtds/packages_1_0.dtd&quot;&gt;
&lt;checkstyle-packages&gt;
&lt;package name=&quot;com.mycompany.checks&quot;/&gt;
&lt;/checkstyle-packages&gt;
</source>
<p>
Now you can configure a module of package <code>com.mycompany.checks</code>, say <code>com.mycompany.checks.MethodLimitCheck</code>, with
a shortened <code>module</code> element in the
configuration document:
</p>
<source>
&lt;module name=&quot;MethodLimit&quot;/&gt;
</source>
<div class="tip">
<b>Note</b>
<p>
As of Checkstyle 5.0 it is unnecessary to repeat the
<code>package</code> elements for Checkstyle's packages in
your custom <code>checkstyle_packages.xml</code> file.
</p>
</div>
</section>
<section name="XML Structure">
<b>Configuration XML Document</b>
<p>
The following DTD for a configuration XML document specifies the
hierarchy of modules and their properties:
</p>
<source>
&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;!ELEMENT module (module|property)*&gt;
&lt;!ATTLIST module name NMTOKEN #REQUIRED&gt;
&lt;!ELEMENT property EMPTY&gt;
&lt;!ATTLIST property
name NMTOKEN #REQUIRED
value CDATA #REQUIRED
&gt;
</source>
<p>
Checkstyle validates a configuration XML document when it loads
the document. To validate against the above configuration DTD,
include the following document type declaration in your
configuration XML document:
</p>
<source>
&lt;!DOCTYPE module PUBLIC
&quot;-//Puppy Crawl//DTD Check Configuration 1.3//EN&quot;
&quot;http://checkstyle.sourceforge.net/dtds/configuration_1_3.dtd&quot;&gt;
</source>
<p>
Checkstyle also strictly enforces the encoding attribute of an
XML declaration. If Checkstyle rejects your configuration
document's encoding, correct the value of the encoding
attribute, or remove the encoding attribute entirely.
</p>
<p>
For a complete example of a configuration XML document, examine
file <code>docs/sun_checks.xml</code> that checks the Sun coding
conventions.
</p>
<b>Package Names XML Document</b>
<p>
This is a DTD for a package names XML document:
</p>
<source>
&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;!ELEMENT checkstyle-packages (package)*&gt;
&lt;!ELEMENT package (package)*&gt;
&lt;!ATTLIST package name NMTOKEN #REQUIRED&gt;
</source>
<p>
Checkstyle also validates a package names XML document when it
loads the document. To validate against the above package names
DTD, include the following document type declaration in your
package names XML document:
</p>
<source>
&lt;!DOCTYPE checkstyle-packages PUBLIC
&quot;-//Puppy Crawl//DTD Package Names 1.1//EN&quot;
&quot;http://checkstyle.sourceforge.net/dtds/packages_1_1.dtd&quot;&gt;
</source>
<b>Suppressions XML Document</b>
<p>
This is a DTD for a suppressions XML document:
</p>
<source>
&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;!ELEMENT suppressions (suppress*)&gt;
&lt;!ELEMENT suppress EMPTY&gt;
&lt;!ATTLIST suppress files CDATA #IMPLIED
checks CDATA #IMPLIED
message CDATA #IMPLIED
id CDATA #IMPLIED
lines CDATA #IMPLIED
columns CDATA #IMPLIED&gt;
</source>
</section>
</body>
</document>