Java Logging Rules

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.rules.MoreThanOneLogger

Example:

                
 
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());
}

     
            

LoggerIsNotStaticFinal

Since: PMD 2.0

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

This rule is defined by the following XPath expression:

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

Example:

                
 
class Foo{
    Logger log = Logger.getLogger(Foo.class.getName());
    // It is much better to declare the logger as follows 
    // static final Logger log = Logger.getLogger(Foo.class.getName());
}

     
            

SystemPrintln

Since: PMD 2.1

System.(out|err).print is used, consider using a logger.

This rule is defined by the following XPath expression:

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

Example:

                
 
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.

This rule is defined by the following XPath expression:


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

             

Example:

                

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