##### Overview

- Download PMD 5.0.4
- What's new in PMD 5.0.4
- 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
- Mvn 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
- Rule guidelines
- PMD developers information
- PMD Release Process

##### For example

- Run PMD on a Sourceforge project

##### Misc.

- XPath tutorial (Gregorian)

##### Rule Sets

- ecmascript
  - Basic Ecmascript
  - Braces
  - Unnecessary
- java
  - Android
  - Basic
  - Braces
  - Clone Implementation
  - Code Size
  - Comments
  - Controversial
  - Coupling
  - Design
  - Empty Code
  - Finalizer
  - Import Statements
  - J2EE
  - JavaBeans
  - JUnit
  - Jakarta Commons Logging
  - Java Logging
  - Migration
  - Naming
  - Optimization
  - Strict Exceptions
  - String and StringBuffer
  - Security Code Guidelines
  - Type Resolution
  - Unnecessary
  - Unused Code
- jsp
  - Basic JSF
  - Basic JSP
- xml
  - Basic XML
- xsl
  - XPath in XSL

##### Project Documentation

- Project Information
- Project Reports

## Java Logging

The Java Logging ruleset contains a collection of rules that find questionable usages of the logger.

### MoreThanOneLogger

Since: PMD 2.0

Normally only one logger is used in each class.

This rule is defined by the following Java class: net.sourceforge.pmd.lang.java.rule.logging.MoreThanOneLoggerRule

Example(s):

    public class Foo {
        Logger log = Logger.getLogger(Foo.class.getName());
        // It is very rare to see two loggers on a class, normally
        // log information is multiplexed by levels
        Logger log2= Logger.getLogger(Foo.class.getName());
    }

This rule has the following properties:

Name | Default Value | Description
violationSuppressRegex |  | Suppress violations with messages matching a regular expression
violationSuppressXPath |  | Suppress violations on nodes which match a given relative XPath expression.

### LoggerIsNotStaticFinal

Since: PMD 2.0

In most cases, the Logger reference can be declared as static and final.

    //VariableDeclarator
     [parent::FieldDeclaration]
     [../Type/ReferenceType
      /ClassOrInterfaceType[@Image='Logger']
       and
      (..[@Final='false'] or ..[@Static = 'false'] ) ]

Example(s):

    public class Foo{
        Logger log = Logger.getLogger(Foo.class.getName());					// not recommended

        static final Logger log = Logger.getLogger(Foo.class.getName());	// preferred approach
    }

### SystemPrintln

Since: PMD 2.1

References to System.(out|err).print are usually intended for debugging purposes and can remain in the codebase even in production code. By using a logger one can enable/disable this behaviour at will (and by priority) and avoid clogging the Standard out log.

    //Name[
        starts-with(@Image, 'System.out.print')
        or
        starts-with(@Image, 'System.err.print')
        ]

Example(s):

    class Foo{
        Logger log = Logger.getLogger(Foo.class.getName());
        public void testA () {
            System.out.println("Entering test");
            // Better use this
            log.fine("Entering test");
        }
    }

### AvoidPrintStackTrace

Since: PMD 3.2

Avoid printStackTrace(); use a logger call instead.

    //PrimaryExpression
     [PrimaryPrefix/Name[contains(@Image,'printStackTrace')]]
     [PrimarySuffix[not(boolean(Arguments/ArgumentList/Expression))]]

Example(s):

    class Foo {
      void bar() {
        try {
         // do something
        } catch (Exception e) {
         e.printStackTrace();
         }
       }
    }