##### 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

## Migration

Contains rules about migrating from one JDK version to another. Don't use these rules directly, rather, use a wrapper ruleset such as migrating_to_13.xml.

### ReplaceVectorWithList

Since: PMD 3.4

Consider replacing Vector usages with the newer java.util.ArrayList if expensive thread-safe operations are not required.

    //Type/ReferenceType/ClassOrInterfaceType[@Image='Vector']

Example(s):

    public class Foo {
     void bar() {
        Vector v = new Vector();
     }
    }

### ReplaceHashtableWithMap

Since: PMD 3.4

Consider replacing Hashtable usage with the newer java.util.Map if thread safety is not required.

    //Type/ReferenceType/ClassOrInterfaceType[@Image='Hashtable']

Example(s):

    public class Foo {
    	void bar() {
    		Hashtable h = new Hashtable();
    	}
    }

### ReplaceEnumerationWithIterator

Since: PMD 3.4

Consider replacing Enumeration usages with the newer java.util.Iterator

    //ImplementsList/ClassOrInterfaceType[@Image='Enumeration']

Example(s):

    public class Foo implements Enumeration {
        private int x = 42;
        public boolean hasMoreElements() {
            return true;
        }
        public Object nextElement() {
            return String.valueOf(i++);
        }
    }

### AvoidEnumAsIdentifier

Since: PMD 3.4

Use of the term 'enum' will conflict with newer versions of Java since it is a reserved word.

    //VariableDeclaratorId[@Image='enum']

Example(s):

    public class A {
    	public  class foo {
    		String enum = "foo";
    	}
    }

### AvoidAssertAsIdentifier

Since: PMD 3.4

Use of the term 'assert' will conflict with newer versions of Java since it is a reserved word.

    //VariableDeclaratorId[@Image='assert']

Example(s):

    public class A {
    	public  class foo {
    		String assert = "foo";
    	}
    }

### IntegerInstantiation

Since: PMD 3.5

Calling new Integer() causes memory allocation that can be avoided by the static Integer.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.

    //PrimaryPrefix
     /AllocationExpression
      [not (ArrayDimsAndInits)
       and (ClassOrInterfaceType/@Image='Integer'
        or ClassOrInterfaceType/@Image='java.lang.Integer')]

Example(s):

    public class Foo {
    	private Integer i = new Integer(0); // change to Integer i = Integer.valueOf(0);
    }

### ByteInstantiation

Since: PMD 4.0

Calling new Byte() causes memory allocation that can be avoided by the static Byte.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.

    //PrimaryPrefix/AllocationExpression
    [not (ArrayDimsAndInits)
    and (ClassOrInterfaceType/@Image='Byte'
    or ClassOrInterfaceType/@Image='java.lang.Byte')]

Example(s):

    public class Foo {
    	private Byte i = new Byte(0); // change to Byte i =	Byte.valueOf(0);
    }

### ShortInstantiation

Since: PMD 4.0

Calling new Short() causes memory allocation that can be avoided by the static Short.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.

    //PrimaryPrefix
    /AllocationExpression
    [not (ArrayDimsAndInits)
    and (ClassOrInterfaceType/@Image='Short'
    or ClassOrInterfaceType/@Image='java.lang.Short')]

Example(s):

    public class Foo {
    	private Short i = new Short(0); // change to Short i = Short.valueOf(0);
    }

### LongInstantiation

Since: PMD 4.0

Calling new Long() causes memory allocation that can be avoided by the static Long.valueOf(). It makes use of an internal cache that recycles earlier instances making it more memory efficient.

    //PrimaryPrefix
    /AllocationExpression
    [not (ArrayDimsAndInits)
    and (ClassOrInterfaceType/@Image='Long'
    or ClassOrInterfaceType/@Image='java.lang.Long')]

Example(s):

    public class Foo {
    	private Long i = new Long(0); // change to Long i = Long.valueOf(0);
    }

### JUnit4TestShouldUseBeforeAnnotation

Since: PMD 4.0

In JUnit 3, the setUp method was used to set up all data entities required in running tests. JUnit 4 skips the setUp method and executes all methods annotated with @Before before all tests

    //ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='setUp']]
    [count(Annotation/MarkerAnnotation/Name[@Image='Before'])=0]

Example(s):

    public class MyTest {
        public void setUp() {
            bad();
        }
    }
    public class MyTest2 {
        @Before public void setUp() {
            good();
        }
    }

### JUnit4TestShouldUseAfterAnnotation

Since: PMD 4.0

In JUnit 3, the tearDown method was used to clean up all data entities required in running tests. JUnit 4 skips the tearDown method and executes all methods annotated with @After after running each test

    //ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='tearDown']]
    [count(Annotation/MarkerAnnotation/Name[@Image='After'])=0]

Example(s):

    public class MyTest {
        public void tearDown() {
            bad();
        }
    }
    public class MyTest2 {
        @After public void tearDown() {
            good();
        }
    }

### JUnit4TestShouldUseTestAnnotation

Since: PMD 4.0

In JUnit 3, the framework executed all methods which started with the word test as a unit test. In JUnit 4, only methods annotated with the @Test annotation are executed.

    //ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[starts-with(@Image,'test')]]
    [count(Annotation//Name[@Image='Test'])=0]

Example(s):

    public class MyTest {
        public void testBad() {
            doSomething();
        }

    	@Test
        public void testGood() {
            doSomething();
        }
    }

### JUnit4SuitesShouldUseSuiteAnnotation

Since: PMD 4.0

In JUnit 3, test suites are indicated by the suite() method. In JUnit 4, suites are indicated through the @RunWith(Suite.class) annotation.

    //ClassOrInterfaceBodyDeclaration[MethodDeclaration/MethodDeclarator[@Image='suite']]
    [MethodDeclaration/ResultType/Type/ReferenceType/ClassOrInterfaceType[@Image='Test' or @Image = 'junit.framework.Test']]
    [not(MethodDeclaration/Block//ClassOrInterfaceType[@Image='JUnit4TestAdapter'])]

Example(s):

    public class BadExample extends TestCase{

        public static Test suite(){
        	return new Suite();
        }
    }

    @RunWith(Suite.class)
    @SuiteClasses( { TestOne.class, TestTwo.class })
    public class GoodTest {
    }

### JUnitUseExpected

Since: PMD 4.0

In JUnit4, use the @Test(expected) annotation to denote tests that should throw exceptions.

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

Example(s):

    public class MyTest {
    	@Test
        public void testBad() {
            try {
                doSomething();
                fail("should have thrown an exception");
            } catch (Exception e) {
            }
        }

    	@Test(expected=Exception.class)
        public void testGood() {
            doSomething();
        }
    }

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.