Java Logging With Abstract Classes

Question

I am working on a project, and am currently working on implementing some logging with log4j and I was curious about how I should go about implementing the logs. The two implementations I am kicking around are as follows:

First Option

Use single log from super class for that class and all sub classes:

public abstract class AbstractFoo {     protected static Log LOG = LogFactory.getLog(AbstractFoo.class);      ... }  public class Foo extends AbstractFoo {     public void someMethod() {         LOG.info("Using abstract log");     } } 

Second Option

Use individual logs for each class, super and subs:

public abstract class AbstractFoo {     private static Log LOG = LogFactory.getLog(AbstractFoo.class);      ... }  public class Foo extends AbstractFoo {     private static Log LOG = LogFactory.getLog(Foo.class);              public void someMethod() {         LOG.info("Using own log");     } } 

What makes more sense and why?

Answer 1

I wouldn't do either. Instead I would make it use the correct class in both cases.

public abstract class AbstractFoo {     protected final Log log = LogFactory.getLog(getClass());      ... }  public class Foo extends AbstractFoo {     public void someMethod() {         log.info("Using abstract log");     } } 

If you are not doing lots of logging (which is a good idea anyway) you can use a method instead.

public abstract class AbstractFoo {     protected Log log() { return LogFactory.getLog(getClass()); }      ... } 

If there is a class which calls this a lot you can override it to give you a cached instance.

Answer 2

This is my solution (final static logger):

public abstract class AbstractFoo {      protected abstract Log getLogger();      public doSomething() {           getLogger().info("log something");      } }  public class Foo extends AbstractFoo {     private static final Log log = Log.getLogger(Foo.class);      protected Log getLogger() {          return log;     }     public doSomethingElse() {           log.info("log somethingElse");     } }