What is the difference between e.printStackTrace(System.out) and e.printStackTrace()?

Question

2 Questions:

1. What is the difference between e.printStackTrace(System.out) and e.printStackTrace()?
2. Is it safe (from the production point of view) to replace e.printStackTrace(System.out) and e.printStackTrace() with log4j using logger.error("", e) if i want to print out the stack trace in my log file?

Answer 1

1. e.printStackTrace() is same as e.printStackTrace(System.err). So, it prints to standard error. e.printStackTrace(System.err). So, it prints to standard error. e.printStackTrace(System.out)` prints to system out.

2. You should never do e.printStackTrace() , System.out.print() , System.err.print() on a production code. You should always use logger methods, and configure your logger.