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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Metrics Checks</title>
<link rel="stylesheet" type="text/css" href="mystyle.css"/>
</head>
<body>
<!-- The header -->
<table border="0" width="100%" summary="header layout">
<tr>
<td><h1>Metrics Checks</h1></td>
<td align="right"><img src="logo.png" alt="Checkstyle Logo"/></td>
</tr>
</table>
<!-- content -->
<table border="0" width="100%" cellpadding="5" summary="body layout">
<tr>
<!--Left menu-->
<td class="menu" valign="top">
<ul>
<li><a href="#BooleanExpressionComplexity">BooleanExpressionComplexity</a></li>
<li><a href="#ClassDataAbstractionCoupling">ClassDataAbstractionCoupling</a></li>
<li><a href="#ClassFanOutComplexity">ClassFanOutComplexity</a></li>
<li><a href="#CyclomaticComplexity">CyclomaticComplexity</a></li>
<li><a href="#JavaNCSS">JavaNCSS</a></li>
<li><a href="#NPathComplexity">NPathComplexity</a></li>
</ul>
</td>
<!--Content-->
<td class="content" valign="top" align="left">
<!-- --><a name="BooleanExpressionComplexity"></a>
<h2>BooleanExpressionComplexity</h2>
<h4>Description</h4>
<p class="body">
Restrict the number of number of <span class="code">&&</span>,
<span class="code">||</span> and <span class="code">^</span> in
an expression.
</p>
<p>
Rationale:
Too many conditions leads to code that is difficult to
read and hence debug and maintain.
</p>
<h4>Properties</h4>
<table width="100%" border="1" cellpadding="5" class="body">
<tr class="header">
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
</tr>
<tr>
<td>max</td>
<td>the maximum allowed number of boolean operations in one
experession.</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">3</span></td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;BooleanExpressionComplexity&quot;/&gt;
</pre>
<p class="body">
To configure the check with 7 allowed operation in boolean expression:
</p>
<pre class="body">
&lt;module name=&quot;BooleanExpressionComplexity&quot;&gt;
&lt;property name=&quot;max&quot; value=&quot;7&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks.metrics
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --><a name="ClassDataAbstractionCoupling"></a> <h2>ClassDataAbstractionCoupling</h2>
<h4>Description</h4>
<p class="body">
This metric measures the number of instantiations of
other classes within the given class. This type of
coupling is not caused by inheritance or the object
oriented paradigm. Generally speaking, any abstract
data type with other abstract data types as members has
data abstraction coupling; therefore, if a class has a
local variable that is an instantiation (object) of
another class, there is data abstraction coupling. The
higher the DAC, the more complex the data structure
(classes) of the system.
</p>
<h4>Properties</h4>
<table width="100%" border="1" cellpadding="5" class="body">
<tr class="header">
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
</tr>
<tr>
<td>max</td>
<td>the maximum threshold allowed</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">7</span></td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;ClassDataAbstractionCoupling&quot;/&gt;
</pre>
<p class="body">
To configure the check with a threshold of 5:
</p>
<pre class="body">
&lt;module name=&quot;ClassDataAbstractionCoupling&quot;&gt;
&lt;property name=&quot;max&quot; value=&quot;5&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks.metrics
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --><a name="ClassFanOutComplexity"></a> <h2>ClassFanOutComplexity</h2>
<h4>Description</h4>
<p class="body">
The number of other classes a given class relies on. Also
the square of this has been shown to indicate the
amount of maintenence required in functional programs
(on a file basis) at least.
</p>
<h4>Properties</h4>
<table width="100%" border="1" cellpadding="5" class="body">
<tr class="header">
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
</tr>
<tr>
<td>max</td>
<td>the maximum threshold allowed</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">20</span></td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;ClassFanOutComplexity&quot;/&gt;
</pre>
<p class="body">
To configure the check with a threshold of 10:
</p>
<pre class="body">
&lt;module name=&quot;ClassFanOutComplexity&quot;&gt;
&lt;property name=&quot;max&quot; value=&quot;10&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks.metrics
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --><a name="CyclomaticComplexity"></a> <h2>CyclomaticComplexity</h2>
<h4>Description</h4>
<p class="body">
Checks cyclomatic complexity against a specified limit. The complexity is
measured by the number of
<span CLASS="code">if</span>,
<span CLASS="code">while</span>,
<span CLASS="code">do</span>,
<span CLASS="code">for</span>,
<span CLASS="code">?:</span>,
<span CLASS="code">catch</span>,
<span CLASS="code">switch</span>,
<span CLASS="code">case</span> statements, and operators
<span CLASS="code">&&</span> and <span CLASS="code">||</span> (plus one) in the body of a
constructor, method, static initializer, or instance initializer.
It is a measure of the minimum number of possible paths through the
source and therefore the number of required tests. Generally 1-4 is
considered good, 5-7 ok, 8-10 consider re-factoring, and 11+ re-factor now!
</p>
<h4>Properties</h4>
<table width="100%" border="1" cellpadding="5" class="body">
<tr class="header">
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
</tr>
<tr>
<td>max</td>
<td>the maximum threshold allowed</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">10</span></td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;CyclomaticComplexity&quot;/&gt;
</pre>
<p class="body">
To configure the check with a threshold of 7:
</p>
<pre class="body">
&lt;module name=&quot;CyclomaticComplexity&quot;&gt;
&lt;property name=&quot;max&quot; value=&quot;7&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks.metrics
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --><a name="NPathComplexity"></a> <h2>NPathComplexity</h2>
<h4>Description</h4>
<p class="body">
The NPATH metric computes the number of possible
execution paths through a function. It takes into
account the nesting of conditional statements and
multi-part boolean expressions (e.g., A && B, C || D,
etc.).
</p>
<p>
Rationale:
Nejmeh says that his group had an informal NPATH limit
of 200 on individual routines; functions that exceeded
this value were candidates for further decomposition -
or at least a closer look.
</p>
<h4>Properties</h4>
<table width="100%" border="1" cellpadding="5" class="body">
<tr class="header">
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
</tr>
<tr>
<td>max</td>
<td>the maximum threshold allowed</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">200</span></td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;NPathComplexity&quot;/&gt;
</pre>
<p class="body">
To configure the check with a threshold of 20:
</p>
<pre class="body">
&lt;module name=&quot;NPathComplexity&quot;&gt;
&lt;property name=&quot;max&quot; value=&quot;20&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks.metrics
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --><a name="JavaNCSS"></a>
<h2>JavaNCSS</h2>
<h4>Description</h4>
<p class="body">
Determines complexity of methods, classes and files by counting
the Non Commenting Source Statements (NCSS).
This check adheres to the <a
href="http://www.kclee.com/clemens/java/javancss/">
specification</a> for the JavaNCSS-Tool written by
<b>Chr. Clemens Lee</b> which sadly seems to have been pulled
off the web.<br/>
Rougly said the NCSS metric is calculated by counting the source
lines which are not comments, (nearly) equivalent to counting
the semicolons and opening curly braces.<br/>
The NCSS for a class is summarized from the NCSS of all its methods,
the NCSS of its nested classes and the number of member variable
declarations.<br/>
The NCSS for a file is summarized from the ncss of all its top level
classes, the number of imports and the package declaration.
</p>
<p>
Rationale:
Too large methods and classes are hard to read and costly to
maintain. A large NCSS number often means that a method or
class has too many responsabilities and/or functionalities
which should be decomposed into smaller units.
</p>
<h4>Properties</h4>
<table width="100%" border="1" cellpadding="5" class="body">
<tr class="header">
<th>name</th>
<th>description</th>
<th>type</th>
<th>default value</th>
</tr>
<tr>
<td>methodMaximum</td>
<td>the maximum allowed number of non commenting lines in
a method.</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">50</span></td>
</tr>
<tr>
<td>classMaximum</td>
<td>the maximum allowed number of non commenting lines in
a class.</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">1500</span></td>
</tr>
<tr>
<td>fileMaximum</td>
<td>the maximum allowed number of non commenting lines in
a file including all top level and nested classes.</td>
<td><a href="property_types.html#integer">integer</a></td>
<td><span class="default">2000</span></td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;JavaNCSS&quot;/&gt;
</pre>
<p class="body">
To configure the check with 40 allowed non commenting lines
for a method:
</p>
<pre class="body">
&lt;module name=&quot;JavaNCSS&quot;&gt;
&lt;property name=&quot;methodMaximum&quot; value=&quot;40&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks.metrics
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
</td>
</tr>
</table>
<hr />
<div><a href="index.html">Back to the Checkstyle Home Page</a></div>
<p class="copyright">
Copyright &copy; 2002-2004 Oliver Burn. All rights Reserved.
</p>
</body>
</html>
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