Does System.out.println violate the law of demeter?

Question

Does System.out.println violate the law of demeter?

If not, why?

Answer 1

Depending on view.

LoD: Yes, because it uses the console. Under LoD you can't assume access.

LoD-F: Yes, because it uses more than one dot. The LoD-F states that in any method usage only the object may know the internal structure of itself. IE

System.out.println() 

requires knowledge of the structure of system (that it has .out) to reach println(),

For System to not break LoD-F it would have to be

System.println()

To break the formal rules down with example, println() (the method) may only access:

1. system itself
2. println()'s parameters
3. any objects created/instantiated within println()
4. system's direct component objects
5. a global variable, accessible by system, in the scope of println()

(I know, it's a reversed reference here as the code should be the method calling it, but it actually swings both ways.)

Answer 2

System.out is actually a "global state", and yes, technically it violates the "law of demeter". But:

• you should avoid using System.out.println(..). Use a logger (log4j, logback, slf4j) instead.
• you are not supposed to rely (and test) anything that's for the purpose of logging to a console. (this does not concern complex logging systems that later aggregate the logged information)