Why log4j's Logger.getLogger() need pass a Class type?

Question

I read some articles about how to use log4j. Most of them give below code as a beginning:

 Logger logger = Logger.getLogger("com.foo.Bar"); 

or

 Logger logger = Logger.getLogger(XXX.class); 

This will initialize the logger object.But my question is why need send the class type as a parameter? It seems when I use the logger, I don't care in which class I use it.So the Class type seems no effect to logger. If I declare a logger as static and public, I can call this logger at another class, So what's the intention of the author to design it like this? Will the Class type bind something when I use the logger? Or I can send any Class types to the getLogger function.

Answer 1

1. You can always use any string as logger name other than class type. It's definitely ok.

2. The reason why many people use class type, I guess:

   • Easy to use. You don't need to worry about logger name duplication in a complex Java EE application. If other people also use your logger name, you may have a log file including no only the output of your class;

   • Easy to check the logging class, as the logger name will show in the log file. You can quickly navigate to the specific class;

   • When you distribute you class, people may want to redirect the logging from your class to a specific file or somewhere else. In such case, if you use a special logger name, we may need to check the source code or imposssible to do that if souce is unavailable.