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. |
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'] ) ]
public class Foo{
Logger log = Logger.getLogger(Foo.class.getName()); // not recommended
static final Logger log = Logger.getLogger(Foo.class.getName()); // preferred approach
}
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') ]
class Foo{
Logger log = Logger.getLogger(Foo.class.getName());
public void testA () {
System.out.println("Entering test");
// Better use this
log.fine("Entering test");
}
}
Since: PMD 3.2
Avoid printStackTrace(); use a logger call instead.
//PrimaryExpression [PrimaryPrefix/Name[contains(@Image,'printStackTrace')]] [PrimarySuffix[not(boolean(Arguments/ArgumentList/Expression))]]
class Foo {
void bar() {
try {
// do something
} catch (Exception e) {
e.printStackTrace();
}
}
}
Since: PMD 5.1.0
Whenever using a log level, one should check if the loglevel is actually enabled, or otherwise skip the associate String creation and manipulation.
This rule is defined by the following Java class: net.sourceforge.pmd.lang.java.rule.logging.GuardLogStatementJavaUtilRule
Example(s):
// Add this for performance
if (log.isLoggable(Level.FINE)) { ...
log.fine("This happens");
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. | |
| guardsMethods | [] | method use to guard the log statement |
| logLevels | [] | LogLevels to guard |