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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>Miscellaneous 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>Miscellaneous 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="#EqualsHashCode">EqualsHashCode</a>
</li>
<li>
<a href="#GenericIllegalRegexp">GenericIllegalRegexp</a>
</li>
<li>
<a href="#HiddenField">HiddenField</a>
</li>
<li>
<a href="#IllegalInstantiation">IllegalInstantiation</a>
</li>
<li>
<a href="#InnerAssignment">InnerAssignment</a>
</li>
<li>
<a href="#SimplifyBooleanExpression">SimplifyBooleanExpression</a>
</li>
<li>
<a href="#SimplifyBooleanReturn">SimplifyBooleanReturn</a>
</li>
<li>
<a href="#TodoComment">TodoComment</a>
</li>
<li>
<a href="#Translation">Translation</a>
</li>
<li>
<a href="#UpperEll">UpperEll</a>
</li>
</ul>
</td>
<!--Content-->
<td class="content" valign="top" align="left"><a name="EqualsHashCode"></a> <h2>EqualsHashCode</h2>
<h4>Description</h4>
<p class="body">
Checks that classes that override <span class="code">equals()</span> also
override <span class="code">hashCode()</span>.
</p>
<p class="body">
Rationale: The contract of <span class="code">equals()</span> and <span class="code">
hashCode()</span> requires that equal objects have the same hashCode. Hence,
whenever you override <span class="code">equals()</span> you must override <span class="code">
hashCode()</span> to ensure that your class can be used in collections that are
hash based.
</p>
<h4>Example</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;EqualsHashCode&quot;/&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="GenericIllegalRegexp"></a> <h2>GenericIllegalRegexp</h2> <h4>Description</h4>
<p class="body">
A generic check for code problems - the user can search for any pattern. This is
similar to a recursive grep, only that it's integrated in checkstyle.
</p>
<p class="body">
Rationale: This check can be used to prototype checks and to find common bad
practice such as calling <span class="code">ex.printStacktrace()</span>, <span class="code">
System.out.println()</span>, <span class="code">System.exit()</span>, etc.
</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>format</td>
<td>illegal pattern</td>
<td><a href="property_types.html#regexp">regular expression</a></td>
<td><span class="default">^$</span> (empty)</td>
</tr>
</table>
<h4>Example</h4>
<p class="body">
To configure the check for calls to <span class="code">System.out.println</span>:
</p>
<pre class="body">
&lt;module name=&quot;GenericIllegalRegexp&quot;&gt;
&lt;property name=&quot;format&quot; value=&quot;System\.out\.println&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="HiddenField"></a> <h2>HiddenField</h2> <h4>Description</h4>
<p class="body">
Checks that a local variable or a parameter does not shadow a field that is
defined in the same class.
</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>tokens</td>
<td>tokens to check</td>
<td>subset of tokens PARAMETER_DEF, VARIABLE_DEF</td>
<td>PARAMETER_DEF, VARIABLE_DEF</td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;HiddenField&quot;/&gt;
</pre>
<p class="body">
To configure the check so that it checks local variables but not parameters:
</p>
<pre class="body">
&lt;module name=&quot;HiddenField&quot;&gt;
&lt;property name=&quot;tokens&quot; value=&quot;VARIABLE_DEF&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="IllegalInstantiation"></a> <h2>IllegalInstantiation</h2> <h4>Description</h4>
<p class="body">
Checks for illegal instantiations where a factory method is preferred.
</p>
<p class="body">
Rationale: Depending on the project, for some classes it might be preferable to
create instances through factory methods rather than calling the constructor.
</p>
<p class="body">
A simple example is the <span class="code">java.lang.Boolean</span> class. In
order to save memory and CPU cycles, it is preferable to use the predefined
constants <span class="code">
TRUE</span> and <span class="code">FALSE</span>. Constructor invocations should
be replaced by calls to <span class="code">Boolean.valueOf()</span>.
</p>
<p class="body">
Some extremely performance sensitive projects may require the use of factory
methods for other classes as well, to enforce the usage of number caches or
object pools.
</p>
<h4>Notes</h4>
<p class="body">
There is a limitation that it is currently not possible to specify array classes.
</p>
<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>classes</td>
<td>classes that should not be instantiated</td>
<td><a href="property_types.html#stringSet">String Set</a></td>
<td>{}</td>
</tr>
</table>
<h4>Example</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;IllegalInstantiation&quot;/&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="InnerAssignment"></a> <h2>InnerAssignment</h2> <h4>Description</h4>
<p class="body">
Checks for assignments in subexpressions, such as in <span class="code">String s
= Integer.toString(i = 2);</span>.
</p>
<p class="body">
Rationale: With the exception of <span class="code">for</span> iterators, all
assignments should occur in their own toplevel statement to increase readability.
With inner assignments like the above it is difficult to see all places where a
variable is set.
</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>tokens</td>
<td>assignments to check</td>
<td>subset of tokens ASSIGN, BAND_ASSIGN, BOR_ASSIGN, BSR_ASSIGN, BXOR_ASSIGN,
DIV_ASSIGN, MINUS_ASSIGN, MOD_ASSIGN, PLUS_ASSIGN, SL_ASSIGN, SR_ASSIGN,
STAR_ASSIGN</td>
<td>all tokens</td>
</tr>
</table>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;InnerAssignment&quot;/&gt;
</pre>
<p class="body">
To configure the check for only <span class="code">=</span>, <span class="code">
+=</span>, and <span class="code">-=</span> operators:
</p>
<pre class="body">
&lt;module name=&quot;InnerAssignment&quot;&gt;
&lt;property name=&quot;tokens&quot; value=&quot;ASSIGN,PLUS_ASSIGN,MINUS_ASSIGN&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="SimplifyBooleanExpression"></a> <h2>SimplifyBooleanExpression</h2>
<h4>Description</h4>
<p class="body">
Checks for overly complicated boolean expressions. Currently finds code like <span class="code">
if (b == true)</span>, <span class="code">b || true</span>, <span class="code">!false</span>, etc.
</p>
<p class="body">
Rationale: Complex boolean logic makes code hard to understand and maintain.
</p>
<h4>Example</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;SimplifyBooleanExpression&quot;/&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="SimplifyBooleanReturn"></a> <h2>SimplifyBooleanReturn</h2> <h4>Description</h4>
<p class="body">
Checks for overly complicated boolean return statements. For example the following code
</p>
<pre class="body">
if (valid())
return false;
else
return true;
</pre>
<p class="body">
could be written as
<pre class="body">
return !valid();
</pre>
</p>
<p class="body">
The Idea for this Check has been shamelessly stolen
from the equivalent <a href="http://pmd.sourceforge.net">PMD</a> rule.
</p>
<h4>Example</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;SimplifyBooleanReturn&quot;/&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="TodoComment"></a> <h2>TodoComment</h2> <h4>Description</h4>
<p class="body">
A check for <span class="code">TODO:</span> comments. Actually it is a generic <a href="http://jakarta.apache.org/regexp/apidocs/org/apache/regexp/RE.html">regular
expression</a> matcher on Java comments. To check for other patterns in Java
comments, set property format.
</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>format</td>
<td>pattern to check</td>
<td><a href="property_types.html#regexp">regular expression</a></td>
<td><span class="default">TODO:</span></td>
</tr>
</table>
<h4>Notes</h4>
<p class="body">
Using <span class="code">TODO:</span> comments is a great way to keep track of
tasks that need to be done. Having them reported by Checkstyle makes it very
hard to forget about them.
</p>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;TodoComment&quot;/&gt;
</pre>
<p class="body">
To configure the check for comments that contain <span class="code">WARNING</span>:
</p>
<pre class="body">
&lt;module name=&quot;TodoComment&quot;&gt;
&lt;property name=&quot;format&quot; value=&quot;WARNING&quot;/&gt;
&lt;/module&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
<!-- --> <a name="Translation"></a> <h2>Translation</h2> <h4>Description</h4>
<p class="body">
A <a href="config.html#overview">FileSetCheck</a> that ensures the correct
translation of code by checking property files for consistency regarding their
keys. Two property files describing one and the same context are consistent if
they contain the same keys.
</p>
<p class="body">
Consider the following properties file in the same directory:
<pre>
#messages.properties
hello=Hello
cancel=Cancel
#messages_de.properties
hell=Hallo
ok=OK
</pre>
<p class="body">
The Translation check will find the typo in the german hello key, the
missing ok key in the default resource file and the missing cancel key
in the german resource file:
<pre>
messages_de.properties: Key 'hello' missing.
messages_de.properties: Key 'cancel' missing.
messages.properties: Key 'hell' missing.
messages.properties: Key 'ok' missing.
</pre>
</p>
<h4 class="body">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>fileExtensions</td>
<td>file type extension to identify translation files. Setting this property
is typically only required if your translation files are preprocessed
and the original files do not have the extension
<span class="code">.properties</span></td>
<td><a href="property_types.html#stringSet">String Set</a></td>
<td><span class="default">properties</span></td>
</tr>
</table>
<h4>Example</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;Translation&quot;/&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#checker">Checker</a>
</p>
<!-- --> <a name="UpperEll"></a> <h2>UpperEll</h2> <h4>Description</h4>
<p class="body">
Checks that long constants are defined with an upper ell. That is <span class="code">'
L'</span> and
not <span class="code">'l'</span>. This is in accordance to the Java Language
Specification, <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">
Section
3.10.1</a>.
</p>
<p class="body"> Rationale: The letter <span class="code">l</span> looks a lot
like <span class="code">1</span>.
</p>
<h4>Examples</h4>
<p class="body">
To configure the check:
</p>
<pre class="body">
&lt;module name=&quot;UpperEll&quot;/&gt;
</pre>
<h4>Package</h4>
<p class="body">
com.puppycrawl.tools.checkstyle.checks
</p>
<h4>Parent Module</h4>
<p class="body">
<a href="config.html#treewalker">TreeWalker</a>
</p>
</td>
</tr>
</table>
<hr />
<p>
Copyright &copy; 2002 Oliver Burn. All rights Reserved.
</p>
</body>
</html>
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