##### Overview

- Download PMD 3.9
- What's new in PMD 3.9
- PMD in the news
- PMD-related products and books
- Best practices
- Future directions
- Similar projects
- Credits
- License
- What does 'PMD' mean?

##### Usage

- Installation
- Command line usage
- Ant task usage
- Maven plugin usage
- IDE plugin usage
- Suppressing warnings
- Finding duplicated code
- JSP support

##### Customizing PMD

- Compiling PMD
- How to write a rule
- Writing XPath rules
- How to make a rule set
- How it works

##### For example

- Run PMD on a Sourceforge project

##### Rule Sets

- Index
- Basic
- Braces
- Code Size
- Clone
- Controversial
- Coupling
- Design
- Finalizers
- Import Statements
- J2EE
- Javabeans
- JUnit Tests
- Logging (Java)
- Logging (Jakarta)
- Migrating
- Naming
- Optimizations
- Strict Exceptions
- Strings
- Sun Security
- Unused Code
- Java Server Pages
- Java Server Faces

##### Project Documentation

- About PMD
- Project Info
- Project Reports
- Development Process

## How to make a new rule set

Say you want to pick specific rules from various rule sets and customize them. You can do this by making your own rule set.

### Create a new ruleset.xml file

Use one of the current rulesets as an example. Copy and paste it into your new file, delete all the old rules from it, and change the name and description. Like this:

    <?xml version="1.0"?>
    <ruleset name="Custom ruleset"
        xmlns="http://pmd.sf.net/ruleset/1.0.0"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd"
        xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">
      <description>
      This ruleset checks my code for bad stuff
      </description>
    </ruleset>

### Add some rule references to it

After you add these references it'll look something like this:

    <?xml version="1.0"?>
    <ruleset name="Custom ruleset"
        xmlns="http://pmd.sf.net/ruleset/1.0.0"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd"
        xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">

      <description>
      This ruleset checks my code for bad stuff
      </description>

      <!-- We'll use the entire 'strings' ruleset -->
      <rule ref="rulesets/strings.xml"/>

      <!-- Here's some rules we'll specify one at a time -->
      <rule ref="rulesets/unusedcode.xml/UnusedLocalVariable"/>
      <rule ref="rulesets/unusedcode.xml/UnusedPrivateField"/>
      <rule ref="rulesets/imports.xml/DuplicateImports"/>
      <rule ref="rulesets/basic.xml/UnnecessaryConversionTemporary"/>

      <!-- We want to customize this rule a bit, change the message and raise the priority  -->
      <rule
       ref="rulesets/basic.xml/EmptyCatchBlock"
       message="Must handle exceptions">
        <priority>2</priority>
      </rule>

      <!-- Now we'll customize a rule's property value -->
      <rule ref="rulesets/codesize.xml/CyclomaticComplexity">
        <properties>
            <property name="reportLevel" value="5"/>
        </properties>
      </rule>

      <!-- Note we want everything from braces.xml except WhileLoopsMustUseBraces -->
      <rule ref="rulesets/braces.xml">
        <exclude name="WhileLoopsMustUseBraces"/>
      </rule>
    </ruleset>

Notice that you can customize individual referenced rules. Everything but the class of the rule can be overridden in your custom ruleset.

### Excluding rules from a ruleset

You can also make a custom ruleset that excludes rules, like this:

    <?xml version="1.0"?>
    <ruleset name="mybraces"
        xmlns="http://pmd.sf.net/ruleset/1.0.0"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd"
        xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">
      <description>Just the braces rules I like</description>
      <rule ref="rulesets/braces.xml">
        <exclude name="WhileLoopsMustUseBraces"/>
        <exclude name="IfElseStmtsMustUseBraces"/>
      </rule>
    </ruleset>

### Reference it in your Ant task

You can specify the full path to your custom ruleset name alongside of the built-in PMD rulesets - like this:

    <pmd rulesetfiles="/home/tom/data/pmd/pmd/rulesets/favorites.xml,rulesets/unusedcode.xml">
      <formatter type="xml" toFile="foo.xml"/>
      <fileset dir="/home/tom/data/pmd/pmd/src">
        <include name="**/*.java"/>
      </fileset>
    </pmd>

### To see it in your IDE, add it to rulesets/rulesets.properties

At least, that's the way some of the IDE plugins do it. Some have other ways of adding custom rulesets.

### Send us feedback

If you have suggestions on clarifying this document, please post them to the forum. Thanks!

Finally, for many more details on building custom rulesets, pick up PMD Applied!