PMD - Java Logging Rules

The twelfth installment of explanation of PMD rules covering Java Logging Rules.

Java Logging Rules

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

MoreThanOneLogger

Normally only one logger is used in each class.

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

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

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

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

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

Avoid printStackTrace(); use a logger call instead.

Example

class Foo {

void bar() {

  try {

   // do something

  } catch (Exception e) {

   e.printStackTrace();

  }

}

}