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<div id="title">
JDepend
</div>
<!--
Summary
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<div id="summary">
<p>
<b><u>Summary</u></b>
</p>
<p>
JDepend traverses Java class file directories and generates design
quality metrics for each Java package. JDepend allows you to
automatically measure the quality of a design in terms of its
extensibility, reusability, and maintainability to manage package
dependencies effectively.
</p>
<p>
<i>If you like this kind of automation, you'll love my book,
<a href="http://www.pragmaticprogrammer.com/sk/auto/">Pragmatic Project
Automation</a>.
</i>
</p>
</div>
<!--
Table of Contents
-->
<div class="header">
Table of Contents
</div>
<ul>
<li><a href="#overview">Overview</a></li>
<li><a href="#uses">Why Use JDepend?</a></li>
<li><a href="#download">Downloading JDepend</a></li>
<li><a href="#installation">Installing JDepend</a></li>
<li><a href="#building">Building and Testing JDepend</a></li>
<li><a href="#howtouse">Running JDepend</a></li>
<li><a href="#graphical">Graphical UI Navigation</a></li>
<li><a href="#cycles">Interpreting Dependency Cycles</a></li>
<li><a href="#customize">Customizing JDepend</a></li>
<li><a href="#junit">Using JDepend With JUnit</a></li>
<li><a href="#fitnesse">Using JDepend With FitNesse</a></li>
<li><a href="#ant">Using JDepend With Ant</a></li>
<li><a href="#limitations">Limitations</a></li>
<li><a href="#support">Support</a></li>
<li><a href="#donate">Donate</a></li>
<li><a href="#reviews">Design Reviews</a></li>
<li><a href="#license">License</a></li>
<li><a href="#credits">Acknowledgments</a></li>
<li><a href="#resources">Resources</a></li>
</ul>
<!--
Overview
-->
<div class="header">
<a name="overview"></a>
Overview
</div>
<p>
JDepend traverses Java class file directories and generates design
quality metrics for each Java package, including:
</p>
<ul>
<li><b>Number of Classes and Interfaces</b>
<p>
The number of concrete and abstract classes (and interfaces) in the
package is an indicator of the extensibility of the package.
</p>
</li>
<li><b>Afferent Couplings (Ca)</b>
<p>
The number of other packages that depend upon classes within
the package is an indicator of the package's responsibility.
</p>
</li>
<li><b>Efferent Couplings (Ce)</b>
<p>
The number of other packages that the classes in the package depend
upon is an indicator of the package's independence.
</p>
</li>
<li><b>Abstractness (A)</b>
<p>
The ratio of the number of abstract classes (and interfaces)
in the analyzed package to the total number of classes in
the analyzed package.
</p>
<p>
The range for this metric is 0 to 1, with A=0 indicating a
completely concrete package and A=1 indicating a completely
abstract package.
</p>
</li>
<li><b>Instability (I)</b>
<p>
The ratio of efferent coupling (Ce) to total coupling
(Ce + Ca) such that I = Ce / (Ce + Ca). This metric is
an indicator of the package's resilience to change.
</p>
<p>
The range for this metric is 0 to 1, with I=0 indicating
a completely stable package and I=1 indicating a completely
instable package.
</p>
</li>
<li><b>Distance from the Main Sequence (D)</b>
<p>
The perpendicular distance of a package from the idealized
line A + I = 1. This metric is an indicator of the package's
balance between abstractness and stability.
</p>
<p>
A package squarely on the main sequence is optimally balanced
with respect to its abstractness and stability. Ideal packages
are either completely abstract and stable (x=0, y=1) or completely
concrete and instable (x=1, y=0).
</p>
<p>
The range for this metric is 0 to 1, with D=0 indicating
a package that is coincident with the main sequence and
D=1 indicating a package that is as far from the main sequence
as possible.
</p>
</li>
<li><b>Package Dependency Cycles</b>
<p>
Package dependency cycles are reported along with the hierarchical
paths of packages participating in package dependency cycles.
</p>
</li>
</ul>
<!--
Uses
-->
<div class="header">
<a name="uses"></a>
Why Use JDepend?
</div>
<p>
Before using JDepend, it is important to understand that
"good" design quality metrics are not necessarily indicative
of good designs. Likewise, "bad" design quality metrics are
not necessarily indicative of bad designs. The design quality metrics
produced by JDepend should not be used as yard sticks by which all
designs are measured.
</p>
<p>
The design quality metrics produced by JDepend are intended to be used
by designers to measure the designs they create, understand those
designs, and automatically check that the designs exhibit expected
qualities while undergoing continuous refactoring. Refactoring will
undoubtedly lead to some adjustment of these metrics as the shape of
the design changes.
</p>
<p>
<b>Measure Design Quality</b>
</p>
<p>
The quality of a design can be measured in part by quantifying its
degrees of extensibility, reusability, and maintainability. These
qualities are all influenced by the inter-package dependencies of the
design. Designs are more extensible when they are independent of
implementation details, allowing them to adapt to new implementations
without internal modification or breaking their existing contracts.
This same independence tends to increase the reuse potential of
portions of the design. Independent portions of the design containing
high-level abstractions can be extracted from portions containing
implementation details.
</p>
<p>
The maintainability of a design is improved when changes can easily be
made without propagating to other parts of the system. JDepend allows
you to automatically measure the quality of a design in terms of its
extensibility, reusability, and maintainability to effectively manage
and control package dependencies.
</p>
<p>
<b>Invert Dependencies</b>
</p>
<p>
The goal of using JDepend is to ultimately invert package dependencies
such that low-abstraction packages depend upon high-abstraction
packages. This inversion of dependencies allows the high-abstraction
packages to be reused independently while being extensible to an open
set of implementations. In general, dependencies upon stable packages
are desirable, while dependencies upon instable packages are
undesirable. JDepend allows dependencies to be iteratively examined
and refactored as an integral part of software design and development.
</p>
<p>
<b>Foster Parallel, Extreme Programming</b>
</p>
<p>
Packages that are stable should be the centerpieces of a loosely
coupled application so the speed of the development team is not
adversely affected by the propagation of software changes. Stable
packages form design-by-contract facades to other subsystems, allowing
teams to develop in parallel at an extreme pace. Moreover, by
measuring the software design quality, the overall impact of proposed
software changes can be accurately estimated. JDepend allows teams to
identify and use desirable dependencies in the system and avoid those
dependencies that cause changes to ripple throughout the system.
</p>
<p>
<b>Isolate Third-Party Package Dependencies</b>
</p>
<p>
Third-party package dependencies can be easily identified and isolated
by examining the afferent couplings to those packages. Once the
dependency on these third-party packages has been measured with
JDepend, the dependency can be managed by effectively designing
abstract and stable packages that encapsulate the third-party package
implementation details.
</p>
<p>
<b>Package Release Modules</b>
</p>
<p>
Packages that are cohesive and independent can be released as
autonomous modules with their own release schedules and version
numbers. Single packages, or groups of related packages collaborating
in a framework, that are candidates for independent release can be
harvested by evaluating their design quality metrics using JDepend.
</p>
<p>
<b>Identify Package Dependency Cycles</b>
</p>
<p>
Packages participating in a package dependency cycle are in a deadly
embrace with respect to reusability and their release cycle. Package
dependency cycles can be easily identified by reviewing the textual
reports of dependency cycles. Once these dependency cycles have been
identified with JDepend, they can be broken by employing various
object-oriented techniques.
</p>
<!--
Download
-->
<div class="header">
<a name="download"></a>
Downloading JDepend
</div>
<p>
<a href="http://www.clarkware.com/software/jdepend-2.9.1.zip">JDepend
2.9</a> is the latest major version release. It includes all the
minor version changes.
</p>
<p>
The distribution contains a JAR file, source code, sample application,
API documentation, and this document.
</p>
<!--
Installation
-->
<div class="header">
<a name="installation"></a>
Installing JDepend
</div>
<p>
<b>Windows</b>
</p>
<p>
To install JDepend, follow these steps:
</p>
<ol>
<li>
<p>
Unzip the <code>jdepend-<version>.zip</code> distribution
file to a directory referred to as <code>%JDEPEND_HOME%</code>.
</p>
</li>
<li>
<p>
Add JDepend to the classpath:
</p>
<p>
<code>set CLASSPATH=%CLASSPATH%;%JDEPEND_HOME%\lib\jdepend-<version>.jar</code>
</p>
</li>
</ol>
<p>
<b>Unix (bash)</b>
</p>
<p>
To install JDepend, follow these steps:
</p>
<ol>
<li>
<p>
Unzip the <code>jdepend-<version>.zip</code> distribution
file to a directory referred to as <code>$JDEPEND_HOME</code>.
</p>
</li>
<li>
<p>
Change file permissions:
</p>
<p>
<code>chmod -R a+x $JDEPEND_HOME</code>
</p>
</li>
<li>Add JDepend to the classpath:
<p>
<code>export CLASSPATH=$CLASSPATH:$JDEPEND_HOME/lib/jdepend-<version>.jar</code>
</p>
</li>
</ol>
<!--
Building
-->
<div class="header">
<a name="building"></a>
Building and Testing JDepend
</div>
<p>
The JDepend distribution includes the pre-built classes in the
<code>$JDEPEND_HOME/lib/jdepend-<version>.jar</code> file.
</p>
<p>
<b>Building</b>
</p>
<p>
An <a href="http://jakarta.apache.org/ant" target="_parent">Ant</a>
build file is included in <code>$JDEPEND_HOME/build.xml</code> to
build the <code>$JDEPEND_HOME/dist/jdepend-<version>.jar</code>
file from the included source code.
</p>
<p>
To build JDepend, use:
</p>
<div>
<blockquote>
<pre>
cd $JDEPEND_HOME
ant jar
</pre>
</blockquote>
</div>
<p>
<b>Testing</b>
</p>
<p>
The JDepend distribution includes
<a href="http://www.junit.org" target="_parent">JUnit</a>
test cases to validate the integrity of JDepend.
</p>
<p>
To test JDepend, use:
</p>
<div>
<blockquote>
<pre>
cd $JDEPEND_HOME
ant test
</pre>
</blockquote>
</div>
<!--
How To Use
-->
<div class="header">
<a name="howtouse"></a>
Running JDepend
</div>
<p>
JDepend provides a graphical, textual, and XML user interface to
visualize Java package metrics, dependencies, and cycles.
</p>
<p>
<b>Graphical UI</b>
</p>
<p>
The graphical user interface displays a hierarchical tree for both the
afferent and efferent couplings of each analyzed Java package.
</p>
<p>
To run JDepend with the graphical user interface, use the following syntax:
</p>
<div>
<blockquote>
<pre>
java jdepend.swingui.JDepend [-components <components>] <directory> [directory2 [directory 3] ...]
</pre>
</blockquote>
</div>
<p>
For example, to analyze all the Java class files in the
<code>$JDEPEND_HOME/build</code> directory, use:
</p>
<div>
<blockquote>
<pre>
java jdepend.swingui.JDepend $JDEPEND_HOME/build
</pre>
</blockquote>
</div>
<p>
<b>Textual UI</b>
</p>
<p>
The textual user interface displays detailed metrics, dependencies,
and cycles for each analyzed Java package. For the convenience of
importing these metrics into other applications, the summary section
contains comma-separated metrics for each Java package.
Alternatively, the XML user interface can be used for easier
integration with other tools.
</p>
<p>
To run JDepend with the textual user interface, use the following
syntax:
</p>
<div>
<blockquote>
<pre>
java jdepend.textui.JDepend [-components <components>] [-file <output file>] <directory> [directory2 [directory 3] ...]
</pre>
</blockquote>
</div>
<p>
For example, to analyze all the Java class files in the
<code>$JDEPEND_HOME/build</code> directory, use:
</p>
<div>
<blockquote>
<pre>
java jdepend.textui.JDepend $JDEPEND_HOME/build
</pre>
</blockquote>
</div>
<p>
Alternatively, the text report can be written to file using:
</p>
<div>
<blockquote>
<pre>
java jdepend.textui.JDepend -file report.txt $JDEPEND_HOME/build
</pre>
</blockquote>
</div>
<p>
<a href="jdepend-text.out" target="_parent">Example output</a> from the
textual UI shows the analysis of the sample application, an example
electronic payment framework. The relevant source for the sample
application is distributed in
<code>$JDEPEND_HOME/sample</code>.
</p>
<p>
<b>XML UI</b>
</p>
<p>
The XML user interface displays detailed metrics, dependencies, and
cycles for each analyzed Java package in an XML format for easier
integration with other tools.
</p>
<p>
To run JDepend with the XML user interface, use the following syntax:
</p>
<div>
<blockquote>
<pre>
java jdepend.xmlui.JDepend [-components <components>] [-file <output file>] <directory> [directory2 [directory 3] ...]
</pre>
</blockquote>
</div>
<p>
For example, to analyze all the Java class files in the
<code>$JDEPEND_HOME/build</code> directory, use:
</p>
<div>
<blockquote>
<pre>
java jdepend.xmlui.JDepend $JDEPEND_HOME/build
</pre>
</blockquote>
</div>
<p>
Alternatively, the XML report can be written to file using:
</p>
<div>
<blockquote>
<pre>
java jdepend.xmlui.JDepend -file report.xml $JDEPEND_HOME/build
</pre>
</blockquote>
</div>
<p>
<a href="jdepend-xml.out" target="_parent">Example output</a> from the
XML UI shows the analysis of the sample application, an example
electronic payment framework. The relevant source for the sample
application is distributed in
<code>$JDEPEND_HOME/sample</code>.
</p>
<p>
You can then transform the XML format into a format of your liking.
For example, David Bock contributed an XSL stylesheet that transforms
the JDepend XML output into a <a
href="http://www.research.att.com/sw/tools/graphviz/"
target="_parent">Graphviz</a> dot file format. David's stylesheet is
distributed with JDepend in the <code>contrib/jdepend2dot.xsl</code>
file.
</p>
<p>
To create a sample Graphviz file, use:
</p>
<div>
<blockquote>
<pre>
ant jdepend-to-graphviz
</pre>
</blockquote>
</div>
<p>
This will create a <code>docs/jdepend-report.dot</code> file. If
you have Graphviz installed, you can then convert that .dot file
into a .png file using:
</p>
<div>
<blockquote>
<pre>
dot -Tpng -o jdepend.png jdepend.dot
</pre>
</blockquote>
</div>
<!--
Graphical UI Navigation
-->
<div class="header">
<a name="graphical"></a>
Graphical UI Navigation
</div>
<p>
The graphical user interface displays the afferent and efferent
couplings of each analyzed Java package, presented in the familiar
Java Swing tree structure.
</p>
<p>
Figure 1 shows the analysis of the sample application, an example
electronic payment framework. The relevant source for the sample
application is distributed in <code>$JDEPEND_HOME/sample</code>.
</p>
<p>
<a href="images/figure1b.jpg" target="_parent">
<img src="images/figure1a.jpg" alt="Figure 1"/>
</a>
<br/>
Figure 1 (Click to view full-scale)
</p>
<p>
The root of each tree displays a branch for each analyzed Java
package, annotated with the following metrics:
</p>
<ul>
<li>
<b>CC</b> - Concrete Class Count
</li>
<li>
<b>AC</b> - Abstract Class (and Interface) Count
</li>
<li>
<b>Ca</b> - Afferent Couplings (Ca)
</li>
<li>
<b>Ce</b> - Efferent Couplings (Ce)
</li>
<li>
<b>A</b> - Abstractness (0-1)
</li>
<li>
<b>I</b> - Instability (0-1)
</li>
<li>
<b>D</b> - Distance from the Main Sequence (0-1)
</li>
<li>
<b>V</b> - Volatility (0-1)
</li>
<li>
<b>Cyclic</b> - If the package contains a dependency cycle
</li>
</ul>
<p>
For organizational purposes, package metrics are only displayed at the
root of each tree. For convenience, selecting any node of the tree
displays the currently selected package's metrics in the status bar.
</p>
<p>
<b>Efferent Couplings</b>
</p>
<p>
The top tree displays the efferent couplings of each analyzed Java
package. Branches of the tree can be opened up to explore packages
that the currently selected package depends upon (Figure 2).
</p>
<p>
<a href="images/figure2b.jpg" target="_parent">
<img src="images/figure2b.jpg" alt="Figure 2"/>
</a>
<br/>
Figure 2 (Click to view full-scale)
</p>
<p>
For the <code>epayment.adapters</code> package, we see that it depends
upon 4 other packages:
the <code>com.abc.epayment</code>, <code>com.xyz.epayment</code>,
<code>epayment.framework</code>, and the <code>epayment.response</code>
packages. Furthermore, it's completely concrete (A=0) and completely
instable (I=1). This balance earns it a spot squarely on the main
sequence (D=0). We can conclude from these metrics that dependencies on
this package are undesirable because it's both dependent and irresponsible.
It's sensitive to modifications made to any of it's efferent couplings and
not accountable to any other package. Therefore, it's important that other
packages in the system not become dependent on this package, as they'll in turn
become fragile by any modifications made to the details of the
<code>epayment.adapters</code> package and its dependencies. As a concrete
package, it's not capable of being extended without being modified.
</p>
<p>
For the <code>epayment.framework</code> package, we see that it does
not depend on any other packages in the application (Ce=0). However,
it is responsible to every other package (Ca=5) while exhibiting a
high degree of abstractness (A=0.83) and stability (I=0). While not
completely balanced, this package is very near the main sequence
(D=0.17). We can conclude from these metrics that dependencies on
this package are desirable because it's both independent and
responsible. It's abstractness also indicates that it's capable of
being extended to accommodate new implementations without being
modified.
</p>
<p>
Packages that were imported, but not analyzed, are not shown in the
efferent dependency tree. Third-party software packages that weren't
analyzed, for example, will not be shown in the efferent tree, as
their efferent dependencies are not available.
</p>
<p>
<b>Afferent Couplings</b>
</p>
<p>
The bottom tree displays the afferent couplings of each analyzed Java
package. Branches of the tree can be opened up to explore packages
that use the currently selected package (Figure 3).
</p>
<p>
<a href="images/figure3b.jpg" target="_parent">
<img src="images/figure3b.jpg" alt="Figure 3"/>
</a>
<br/>
Figure 3 (Click to view full-scale)
</p>
<p>
For the <code>epayment.adapters</code> package, we see that it is not
used by any other package in the application. This confirms our
observations of the efferent dependency tree.
</p>
<p>
For the <code>epayment.framework</code> package, we see that it's used
by all the other user-defined packages in the framework. However, it
does not have any efferent couplings (Ce=0) and exhibits a high degree
of abstractness (A=0.83) and stability (I=0). This is a requirement
of a software framework - we want it to be heavily used, thereby
making it very responsible to its clients, yet be highly abstract to
allow extensibility without modification.
</p>
<p>
For the <code>com.abc.epayment</code> package, a third-party software
package, we see that it's used by the <code>epayment.adapters</code>
package. There are no metrics displayed for this package however, as
it's a third-party package that was not analyzed by JDepend. It was
imported by a user-defined package (<code>epayment.adapters</code>),
so it is shown in the afferent dependency tree.
</p>
<p>
Using the afferent dependency tree, it's easy to identify which
user-defined packages are dependent upon third-party software
packages.
</p>
<!--
Interpreting Dependency Cycles
-->
<div class="header">
<a name="cycles"></a>
Interpreting Dependency Cycles
</div>
<p>
Package dependency cycles are best observed using the textual or XML
user interface. In general, all packages dependencies that intersect
a dependency cycle are reported. This includes packages directly
participating in a cycle and packages that depend on packages directly
participating in a cycle.
</p>
<p>
The intent is to identify sets of packages that must be reused and
released together. To break reported cycles, focus on those packages
directly participating in a cycle.
</p>
<p>
Here's an example of a two-package cycle, as reported by the textual UI:
</p>
<div>
<blockquote>
<pre>
com.xyz.ejb
|
| com.xyz.servlet
|-> com.xyz.ejb
</pre>
</blockquote>
</div>
<p>
This indicates that the <code>com.xyz.ejb</code> package depends on
the
<code>com.xyz.servlet</code> package, which in turn depends on the
<code>com.xyz.ejb</code> package. These two package must be released and
reused together.
</p>
<p>
Here's an example of a package that depends on the two-package cycle
described above, as reported by the textual UI:
</p>
<div>
<blockquote>
<pre>
com.xyz.client
|
|-> com.xyz.ejb
| com.xyz.servlet
|-> com.xyz.ejb
</pre>
</blockquote>
</div>
<p>
This indicates that the <code>com.xyz.client</code> package depends on
the <code>com.xyz.ejb</code> package, which in turn forms a cyclic
dependency with the <code>com.xyz.servlet</code> package.
The <code>com.xyz.client</code> package itself isn't part of the
cycle, but since it depends on a package in the cycle, it can't be
reused/released without it.
</p>
<!--
Customizing
-->
<div class="header">
<a name="customize"></a>
Customizing JDepend
</div>
<p>
JDepend can be customized by using command-line options and/or by
creating a <code>jdepend.properties</code> file in the user's home
directory or any directory in the classpath.
</p>
<p>
<b>Components</b>
</p>
<p>
JDepend can calculate metrics and dependencies for components:
packages that contain one or more sub-packages.
</p>
<p>
For example, given the following package hierarchy:
</p>
<div>
<blockquote>
<pre>
com.xyz.package_a.subpackage_a
com.xyz.package_a.subpackage_b
com.xyz.package_a.subpackage_c
com.xyz.package_b.subpackage_a
com.xyz.package_b.subpackage_b
</pre>
</blockquote>
</div>
<p>
Assume you want to collect metrics and dependencies for the
<code>com.xyz.package_a</code> and <code>com.xyz.package_b</code>
packages, but not for any of their contained packages. For example,
if there is a dependency from <code>com.xyz.package_a.subpackage_a</code>
to <code>com.xyz.package_b.subpackage_b</code>, then you want it
to be reported as a dependency from <code>com.xyz.package_a</code>
to <code>com.xyz.package_b.subpackage_b</code>.
</p>
<p>
To do that, use the <code>-components</code> command-line argument:
</p>
<div>
<blockquote>
<pre>
java jdepend.textui.JDepend -components com.xyx.package_a,com.xyz.package_b /path/to/classes
</pre>
</blockquote>
</div>
<p>
Note that if component packages are named using the
<code>-components</code> option, then no other packages
are reported.
</p>
<p>
<b>Package Filters</b>
</p>
<p>
JDepend will ignore all package names specified as values to the
<code>ignore</code> property name prefix in the
<code>jdepend.properties</code> file. By default, no packages are filtered.
</p>
<p>
The following example <code>jdepend.properties</code> file will ignore
all package names prefixed by <code>java</code>, <code>javax</code>,
<code>sun</code>, <code>com.sun</code>, and the package
<code>com.xyz.tests</code>:
</p>
<div>
<blockquote>
<pre>
ignore.java=java.*,javax.*
ignore.sun=sun.*,com.sun.*
ignore.tests=com.xyz.tests
</pre>
</blockquote>
</div>
<p>
Packages can also be filtered programmatically by creating a
<code>PackageFilter</code> instance defining the filters and
then passing it to the <code>JDepend</code> constructor.
</p>
<p>
The following example will ignore all package names prefixed by
<code>java</code> and <code>javax</code>, in addition to any
package filters specified in an existing
<code>jdepend.properties</code> file:
</p>
<div>
<blockquote>
<pre>
PackageFilter filter = new PackageFilter();
filter.addPackage("java.*");
filter.addPackage("javax.*");
JDepend jdepend = new JDepend(filter);
</pre>
</blockquote>
</div>
<p>
The following example will ignore only the package names prefixed
by <code>java</code> and <code>javax</code>, regardless of any package
filters specified in an existing
<code>jdepend.properties</code> file:
</p>
<div>
<blockquote>
<pre>
Collection filters = new ArrayList();
filters.add("java.*");
filters.add("javax.*");
PackageFilter filter = new PackageFilter(filters);
JDepend jdepend = new JDepend(filter);
</pre>
</blockquote>
</div>
<p>
<b>Volatility</b>
</p>
<p>
Packages that are not expected to change can be specifically
configured with a volatility (V) value in the
<code>jdepend.properties</code> file.
V can either be 0 or 1. If V=0, meaning the package is not at
all subject to change, then the package will automatically fall
directly on the main sequence (D=0). If V=1, meaning that the
package is subject to change, then the distance from the main
sequence is not affected. By default, all packages are
configured with V=1.
</p>
<p>
For example, a package like <code>java.lang</code> is generally not
volatile. That is, for all practical purposes this package is
maximally stable. Creating dependencies on it is not cause for
concern. Thus, if you include this package in analysis, it's best to
set its V=0.
</p>
<p>
The following example <code>jdepend.properties</code> file will set
the <code>java.lang</code> package's volatility to 0:
</p>
<div>
<blockquote>
<pre>
java.lang=0
</pre>
</blockquote>
</div>
<p>
Volatility can also be programmatically set on individual packages
prior to analysis by creating a package instance, setting its
volatility, then registering it with the
<code>JDepend</code> instance before analysis.
</p>
<p>
The following example sets V=0 for the <code>java.lang</code> package:
</p>
<div>
<blockquote>
<pre>
JavaPackage javaLang = new JavaPackage("java.lang");
javaLang.setVolatility(0);
// or
JavaPackage javaLang = new JavaPackage("java.lang", 0);
JDepend jdepend = new JDepend();
jdepend.addDirectory("/path/to/classes");
jdepend.addPackage(javaLang);
jdepend.analyze();
</pre>
</blockquote>
</div>
<p>
Wildcards are not supported for configuring sets of packages with a
volatility value.
</p>
<p>
<b>Inner Classes</b>
</p>
<p>
By default, inner classes are analyzed.
</p>
<p>
The following example <code>jdepend.properties</code> file will
disable analyzing inner classes:
</p>
<div>
<blockquote>
<pre>
analyzeInnerClasses=false
</pre>
</blockquote>
</div>
<!--
JUnit
-->
<div class="header">
<a name="junit"></a>
Using JDepend With JUnit
</div>
<p>
In the spirit of automation, metrics can be automatically collected by
JDepend so that they never go stale or require visual inspection. As
the software evolves through refactorings, the design quality test
cases can be run as a sanity check to ensure that the design has not
formed too many undesirable dependencies.
</p>
<p>
Tolerances for any collected metrics (e.g., the distance from the main
sequence (D)) can be codified in a
<a href="http://www.junit.org" target="_parent">JUnit</a> test case
that automatically checks the metrics for conformance to a desired
result and provides immediate visual feedback. Tests can also be
written to fail if any package dependency other than those declared in
a dependency constraint are detected. The existence of package
dependency cycles can also be automatically checked by a JUnit test.
</p>
<p>
<b>Dependency Constraint Tests</b>
</p>
<p>
The following example JUnit test case tests whether a package
dependency constraint is met. This test fails if any package
dependency other than those declared in the dependency constraint are
detected:
</p>
<div class="code-header">
JUnit Package Dependency Constraint Test
</div>
<div class="code">
<pre>
import java.io.*;
import java.util.*;
import junit.framework.*;
public class ConstraintTest extends TestCase {
private JDepend jdepend;
public ConstraintTest(String name) {
super(name);
}
protected void setUp() throws IOException {
jdepend = new JDepend();
jdepend.addDirectory("/path/to/project/util/classes");
jdepend.addDirectory("/path/to/project/ejb/classes");
jdepend.addDirectory("/path/to/project/web/classes");
}
/**
* Tests that the package dependency constraint
* is met for the analyzed packages.
*/
public void testMatch() {
DependencyConstraint constraint = new DependencyConstraint();
JavaPackage ejb = constraint.addPackage("com.xyz.ejb");
JavaPackage web = constraint.addPackage("com.xyz.web");
JavaPackage util = constraint.addPackage("com.xyz.util");
ejb.dependsUpon(util);
web.dependsUpon(util);
jdepend.analyze();
assertEquals("Dependency mismatch",
true, jdepend.dependencyMatch(constraint));
}
public static void main(String[] args) {
junit.textui.TestRunner.run(ConstraintTest.class);
}
}
</pre>
</div>
<p>
<b>Dependency Cycle Tests</b>
</p>
<p>
The following example JUnit test case tests for the existence of
package dependency cycles:
</p>
<div class="code-header">
JUnit Package Dependency Cycle Test
</div>
<div class="code">
<pre>
import java.io.*;
import java.util.*;
import junit.framework.*;
public class CycleTest extends TestCase {
private JDepend jdepend;
public CycleTest(String name) {
super(name);
}
protected void setUp() throws IOException {
jdepend = new JDepend();
jdepend.addDirectory("/path/to/project/ejb/classes");
jdepend.addDirectory("/path/to/project/web/classes");
jdepend.addDirectory("/path/to/project/thirdpartyjars");
}
/**
* Tests that a single package does not contain
* any package dependency cycles.
*/
public void testOnePackage() {
jdepend.analyze();
JavaPackage p = jdepend.getPackage("com.xyz.ejb");
assertEquals("Cycle exists: " + p.getName(),
false, p.containsCycle());
}
/**
* Tests that a package dependency cycle does not
* exist for any of the analyzed packages.
*/
public void testAllPackages() {
Collection packages = jdepend.analyze();
assertEquals("Cycles exist",
false, jdepend.containsCycles());
}
public static void main(String[] args) {
junit.textui.TestRunner.run(CycleTest.class);
}
}
</pre>
</div>
<p>
<b>Main Sequence Distance Tests</b>
</p>
<p>
The following example JUnit test case tests the conformance of
packages to a distance from the main sequence (D) within
project-defined tolerances:
</p>
<div class="code-header">
JUnit Main Sequence Distance Test
</div>
<div class="code">
<pre>
import java.io.*;
import java.util.*;
import junit.framework.*;
public class DistanceTest extends TestCase {
private JDepend jdepend;
public DistanceTest(String name) {
super(name);
}
protected void setUp() throws IOException {
jdepend = new JDepend();
jdepend.addDirectory("/path/to/project/ejb/classes");
jdepend.addDirectory("/path/to/project/web/classes");
jdepend.addDirectory("/path/to/project/thirdpartyjars");
}
/**
* Tests the conformance of a single package to a
* distance from the main sequence (D) within a
* tolerance.
*/
public void testOnePackage() {
double ideal = 0.0;
double tolerance = 0.125; // project-dependent
jdepend.analyze();
JavaPackage p = jdepend.getPackage("com.xyz.ejb");
assertEquals("Distance exceeded: " + p.getName(),
ideal, p.distance(), tolerance);
}
/**
* Tests the conformance of all analyzed packages to a
* distance from the main sequence (D) within a tolerance.
*/
public void testAllPackages() {
double ideal = 0.0;
double tolerance = 0.5; // project-dependent
Collection packages = jdepend.analyze();
Iterator iter = packages.iterator();
while (iter.hasNext()) {
JavaPackage p = (JavaPackage)iter.next();
assertEquals("Distance exceeded: " + p.getName(),
ideal, p.distance(), tolerance);
}
}
public static void main(String[] args) {
junit.textui.TestRunner.run(DistanceTest.class);
}
}
</pre>
</div>
<!--
FitNesse
-->
<div class="header">
<a name="fitnesse"></a>
Using JDepend With FitNesse
</div>
<p>
Writing JUnit tests to detect unwanted dependencies and package cycles
can be awkward. Bob Martin contributed the <a
href="http://www.butunclebob.com/ArticleS.UncleBob.JdependFixture"
target="_parent">Module Dependencies FitNesse fixture</a> that allows
you to represent your package dependencies as a table. The fixture
uses the JDepend API to ensure that only the dependencies declared in
the table actually exist in your software.
</p>
<p>
For example, the following table describes a system with three
components: <code>ejb</code>,
<code>web</code>, and <code>util</code>. The <code>ejb</code>
and <code>web</code> components depend upon the <code>util</code>
component.
</p>
<center>
<table border="1" cellspacing="0" cellpadding="5">
<tr>
<td colspan="4">Module Dependencies</td>
</tr>
<tr>
<td> </td>
<td>ejb</td>
<td>web</td>
<td>util</td>
</tr>
<tr>
<td>ejb</td>
<td> </td>
<td style="background-color: #FFAAAA"> </td>
<td style="background-color: #AAFFAA" align="center">X</td>
</tr>
<tr>
<td>web</td>
<td> </td>
<td> </td>
<td style="background-color: #AAFFAA" align="center">X</td>
</tr>
<tr>
<td>util</td>
<td> </td>
<td> </td>
<td> </td>
</tr>
</table>
</center>
<p>
When this table is executed as a <a href="http://fitnesse.org"
target="_parent">FitNesse</a> fixture, and if the <code>ejb</code>
and <code>web</code> components actually did depend upon
the <code>util</code> component, then the cells containing an X would
be colored green. Any other unexpected component dependencies, such
as the <code>ejb</code> component depending on the <code>web</code>
component, would result in the corresponding cell turning red.
</p>
<p>
Cycles result in all corresponding cells within the cycle to turn red
and be marked with the word 'cycle'. The fixture sports other handy
features, as well. Refer to <a
href="http://www.butunclebob.com/ArticleS.UncleBob.JdependFixture"
target="_parent">Bob's blog</a> for detailed usage information.
</p>
<p>
The <a
href="http://www.butunclebob.com/ArticleS.UncleBob.JdependFixture"
target="_parent">Module Dependencies fixture</a> is distributed with
JDepend in the <code>contrib/fitnesse</code> directory.
</p>
<!--
Ant
-->
<div class="header">
<a name="ant"></a>
Using JDepend With Ant
</div>
<p>
<a href="http://jakarta.apache.org/ant" target="_parent">Ant</a>
includes a task for automatically running JDepend.
</p>
<p>
Java class file directories to analyze are defined by the nested
<code><classespath></code> element.
</p>
<p>
<b>Text Reports</b>
</p>
<p>
The following example Ant task runs JDepend on the <code>build</code>
directory and writes the text report to
the <code>docs/jdepend-report.txt</code> file:
</p>
<div class="code-header">
JDepend Ant Task
</div>
<div class="code">
<pre>
<target name="jdepend">
<jdepend outputfile="docs/jdepend-report.txt">
<exclude name="java.*"/>
<exclude name="javax.*"/>
<classespath>
<pathelement location="build" />
</classespath>
<classpath location="build" />
</jdepend>
</target>
</pre>
</div>
<p>
<b>XML Reports</b>
</p>
<p>
Ant 1.5 and above includes a <code>format</code> attribute for the
JDepend Ant task and a default XSL stylesheet to transform a JDepend
XML report into an HTML report.
</p>
<p>
The following example Ant task runs JDepend on the <code>build</code>
directory, writes the XML report to
the <code>docs/jdepend-report.xml</code> file, and generates
the <code>jdepend.html</code> file using the <code>jdepend.xsl</code>
stylesheet distributed with Ant 1.5 (and above) in
the <code>etc</code> directory:
</p>
<div class="code-header">
JDepend Ant Task
</div>
<div class="code">
<pre>
<target name="jdepend">
<jdepend format="xml" outputfile="docs/jdepend-report.xml">
<exclude name="java.*"/>
<exclude name="javax.*"/>
<classespath>
<pathelement location="classes" />
</classespath>
<classpath location="classes" />
</jdepend>
<style basedir="docs" destdir="docs"
includes="jdepend-report.xml"
style="${ant.home}/etc/jdepend.xsl" />
</target>
</pre>
</div>
<!--
Limitations
-->
<div class="header">
<a name="limitations"></a>
Limitations
</div>
<p>
JDepend has the following known limitations:
</p>
<ul>
<li>
<p>
Cyclic dependency detection may not report all cycles reachable
from a given package. The detection algorithm stops once any
given cycle is detected. If the same cycle is reachable from
another package, the cycle may be reported more than once. In
general, you want to aggressively remove any cycles.
</p>
</li>
<li>
<p>
JDepend does not collect source code complexity metrics. If you
are interested in collecting these types of metrics, the
JavaNCSS tool referenced in the <a
href="#resources">Resources</a> section is recommended.
</p>
</li>
<li>
<p>
The design quality metrics generated by JDepend are imperfect.
They are intended to be used to pragmatically and responsibly
measure design quality in a relative sense, rather than as a
yard stick for all designs.
</p>
</li>
<li>
<p>
Java interfaces are treated as equals with Java abstract
classes. In other words, although there are practical design
advantages to using interfaces in concert with abstract classes,
JDepend treats them uniformly in the calculation of
abstractness. Likewise, abstract classes that implement
interfaces are counted as abstract classes, in addition to their
interface, regardless of whether they are always referenced
outside the package as their interface type.
</p>
</li>
<li>
<p>
JDepend does not currently support the calculation of Ca and Ce
in terms of the number of classes inside a package that have
afferent or efferent couplings to classes inside other packages.
Rather, JDepend calculates Ca and Ce strictly in terms of the
number of packages with which a package has afferent or efferent
couplings, based on the collective analysis of all imported
packages. This deviates slightly from the original Ca and Ce
definitions proposed by Robert Martin.
</p>
</li>
</ul>
<!--
Support
-->
<div class="header">
<a name="support"></a>
Support
</div>
<p>
If you have any questions, comments, enhancement requests, success
stories, or bug reports regarding JDepend, or if you want to be
notified when new versions of JDepend are available, please email
<a href="mailto:mike@clarkware.com">mike@clarkware.com</a>.
Your information will be kept private.
</p>
<p>
A <a href="http://groups.yahoo.com/group/jdepend/"
target="_parent">mailing list</a> is also available to discuss JDepend
or to be notified when new versions of JDepend are available.
</p>
<!--
Donate
-->
<div class="header">
Donate
<a name="donate"></a>
</div>
<p>
Please support the ongoing development of JDepend by purchasing a copy
of the book <a
href="http://www.pragmaticprogrammer.com/sk/auto/">Pragmatic Project
Automation</a>.
</p>
<p>
Thanks in advance!
</p>
<!--
Design Reviews
-->
<div class="header">
<a name="reviews"></a>
Design Reviews
</div>
<p>
Move forward with confidence by getting a timely and valuable second
opinion on your design and/or code. You get an in-depth evaluation
that includes a presentation of the key recommendations and a full
written report of observations and detailed recommendations.
</p>
<p>
<a href="mailto:mike@clarkware.com">Contact me</a> for more details.
</p>
<!--
License
-->
<div class="header">
<a name="license"></a>
License
</div>
<p>
JDepend is licensed under the
<a href="http://www.clarkware.com/software/license.txt">BSD License</a>.
</p>
<!--
Credits
-->
<div class="header">
<a name="credits"></a>
Acknowledgments
</div>
<p>
Many thanks to Robert Martin for originally describing these design
quality metrics and writing the C++ dependency analyzer from which
JDepend was adapted. I am especially grateful that he allowed me to
stand on his shoulders in adapting his work for the Java community.
</p>
<!--
Resources
-->
<div class="header">
<a name="resources"></a>
Resources
</div>
<ul>
<li>
<p>
<a href="http://www.amazon.com/exec/obidos/ASIN/0135974445/clarkware-20"
target="_parent">
"Agile Software Development: Principles, Patterns,
and Practices"</a>, by Martin, R. (Prentice Hall, 2002)
</p>
</li>
<li>
<p>
<a href="http://www.amazon.com/exec/obidos/ASIN/0132038374/clarkware-20"
target="_parent">
"Designing Object-Oriented C++ Applications Using The
Booch Method"</a>, by Martin, R. (Prentice Hall, 1995)
</p>
</li>
<li>
<p>
<a href="http://www.objectmentor.com/publications/oodmetrc.pdf"
target="_parent">"Object Oriented Design Quality Metrics:
An Analysis of Dependencies"</a>, by Martin, R.
</p>
</li>
<li>
<p>
<a href="http://www.kclee.com/clemens/java/javancss"
target="_parent">JavaNCSS</a> - Clemens Lahme's JavaNCSS
measures Non-Commenting Source Statements (NCSS),
the Cyclomatic Complexity Number (McCabe metric), and
other quantitative source-level metrics.
</p>
</li>
</ul>
<div id="copyright">
Copyright © 1999-2005 Clarkware Consulting, Inc.
<br/>
All Rights Reserved
</div>
</body>
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