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<title>Developer guide for Commons "Lang"</title>
<!-- $Id$ -->
<section name='Developer guide for Commons "Lang"'>
<div align="center">
<h1>The Commons <em>Lang</em> Package</h1>
<h2>Developers Guide</h2>
<br />
<a href="#Introduction">[Introduction]</a>
<a href="#PackageStructure">[Package Structure]</a>
<a href="#UtilityClasses">[Utility Classes]</a>
<a href="#Javadoc">[Javadoc]</a>
<a href="#Building">[Building]</a>
<br /><br />
<a name="Introduction"></a>
<h3>1. INTRODUCTION</h3>
<p>The <em>Lang</em> package contains a set of Java classes that extend
the basic JDK classes. This developer guide seeks to set
out rules for the naming of classes and methods within the package. The purpose
of this, as with all naming standards, is to improve the coherency and
consistency of the whole API.</p>
<p>The philosophy of the naming standards is to follow those of the JDK
if possible.</p>
<a name="PackageStructure"></a>
<p>The main package for Lang is <code>org.apache.commons.lang</code>. Subpackages should
be created for each group of related items. </p>
<p>Each package should have a <code>package.html</code> file for javadoc. This should
describe the use of the package and its scope.</p>
<a name="UtilityClasses"></a>
<p>Utility classes provide additional functionality around a class or interface.
Examples include StringUtils and SerializationUtils.</p>
<p>Each class shall follow the naming pattern XxxUtils where Xxx relates to the
class or interface that the utility services. Variations on a theme (<code>Integer</code>
as opposed to <code>Number</code>) should be dealt with in one Utils class where possible.
Each Utils class shall:</p>
<li>be a single, static method based, class</li>
<li>have a name consisting of the interface name plus 'Utils'</li>
<li>deal with one class or interface and its variations (subclasses)</li>
<li>provide methods that perform useful utility functions</li>
<li>the class will not be final</li>
<li>for null parameters, rather than throwing an Exception, consider performing a Null patterned concept, such as returning 0 or ""</li>
<p>A utility class can act as a factory for specific implementations of a class or
interface. In such cases the implementations should be non-public, static, inner classes
of the utility class. However, if warranted due to maintenance or other reasons, these
decorator classes may be moved to top-level classes in a subpackage. The
naming of such a subpackage should be discussed and agreed upon on the
developers mailing list.</p>
<p>If different overloaded variants of a method are desired, with the same method signature, it should not be indicated via a boolean argument, but via a more focused method name. Rather than replace(boolean repeat), replace and replaceAll, or replaceOnce and replace. </p>
<a name="Javadoc"></a>
<h3>4. JAVADOC</h3>
<p>The Sun javadoc guidelines are the starting point for Lang. These points are
an extension to make it easier for users reading the generated
docs and developers with javadoc-popup capabilities from within their IDE.</p>
<p>References to other objects, interfaces or methods use the @link-tag the
first time it is referenced in a class or interface. On the following
references always enclose it inside &lt;code&gt;&lt;/code&gt;.</p>
<p>References to <code>null</code>, <code>this</code>, <code>long</code>,
<code>int</code>, <code>short</code>, <code>char</code>, <code>byte</code>,
<code>double</code>, <code>float</code> and <code>boolean</code> should be enclosed
in &lt;code&gt;&lt;/code&gt;.</p>
<p>Use a short description of what the class/interface/method is used for,
enclose with &lt;p&gt;&lt;/p&gt;.</p>
<p>A longer description about what the class/interface/method is used for
and if it is needed how it is done. If it is necessary include
description of the parameters, what they are used for and how. Enclose
with &lt;p&gt;&lt;/p&gt; where it is needed, try to divide into smaller parts (not
to small!) to enhance readability of the generated Javadoc.</p>
<p>If an example is needed enclose it with &lt;pre&gt;&lt;/pre&gt;.
It should be supported with an explanation within a normal paragraph.</p>
<h4>Exception throwing</h4>
<p>When throwing an exception to indicate a bad argument, always try to throw
IllegalArgumentException, even if the argument was null. Do not throw
NullPointerException. (Obviously, you should document what the code actually does!)</p>
<p>When deprecating a method or class include a clear reference to when the method will be deleted.
This should be of the form 'Method will be removed in Commons Lang 3.0.'. </p>
<h4>Language used in code/comments</h4>
<p>It has been decided to casually standardize on US-English.
To avoid misplaced jeers of 'americanisation', the people making this decision largely write in non-US-English.
However, it's not something to get worked up about.
Lots of spelling differences will creep in all over.</p>
<a name="Building"></a>
<h4>Building a Release</h4>
Commons Lang is intended to interoperate with older versions of Java. To
achieve this, the distribution must be built with the minimum targetted JDK. Why? Over time the
base JDK has changed. Building with a later JDK would make some things in Commons
Lang not run with prior libraries. For example, new StringBuffer(StringBuffer)
was added after JDK1.2, but compiling under 1.4 could link to it. Run the code
under 1.2 and you get a NoSuchMethodError.
The currently targetted version of Java is 1.3.
To build Lang:
<tr><th></th><th>Tested JAR</th><th>Distribution</th><th>Site</th></tr>
<tr><td>ANT 1.6+ (junit.jar in $ANT_HOME/lib)</td><td><code>ant test</code></td><td><code>ant dist</code></td><td>n/a</td></tr>
<tr><td>Maven 1.x</td><td><code>maven jar</code></td><td><code>maven dist</code></td><td><code>maven site</code></td></tr>
<tr><td>Maven 2.x</td><td><code>mvn package</code></td><td>n/a</td><td>n/a</td></tr>