javaeclipseloggingstderrjava.util.logging

Why does java.util.logging.Logger print to stderr?

I've got a simple setup to log a message: Java 8 Update 65 and Eclipse Mars:

import java.util.logging.Logger;

public class Example {

    private final static Logger LOGGER = Logger.getLogger(Example.class.getName());

    public static void main(String[] args) {
        LOGGER.info("Test");
    }

}

I would expect to get an output on the stdout, just like using System.out.println();, but instead it gets printed out on the stderr, which results in a red font on the eclipse console:

enter image description here

I know that I can change this behavior by writing a custom Handler, but I wish to know why the default output appears on the stderr instead of stdout?

A logger should use stdout for fine+info and use stderr for severe level.

Solution

  • By default, the logger outputs log records of level INFO and above (i.e., INFO, WARNING and SEVERE) to standard error stream (System.err).

    Source: www3.ntu.edu.sg/home/ehchua/programming/java/JavaLogging.html