I'm using eclipse IDE, and sometimes, depending on the code, System.err output is printed before than System.out's. For instance:
public static void main(String[] args) {
System.out.println("Regular text"); //1
System.err.println("Error text"); //2
}
With that code, everything is fine. 2 is printed after 1. However, adding some extra system.out sentences reverses the order:
public static void main(String[] args) {
System.out.println("Regular text"); //1
System.err.println("Error text"); //2
//Additional printing stuff
for(String s = "a";s.length() < 200; s = s.concat("" + (char)(s.charAt(s.length()-1)+ 1))){
System.out.println(s);
}
}
1 is printed after 2.
How is this possible?
On some OSes (*nix in particular), the standard output stream is buffered -- that is, whatever gets sent to it might sit around a bit before being sent to the terminal/screen. Standard error, however, often is not buffered, or is auto-flushed after each output.
System.out and System.err are just Java's objects to represent those two streams, and thus, tend to behave as they would on the host platform. But i'm not aware of anything that specifically says they have to.