Timing issues with PrintStreams

Question

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?