Question

I was running some code that did a printout in a swingworker. I was not getting printouts so I used SwingUtilities.invokeLater and now it works. I did not expect this result, how did this happen? I would have thought System.out.println could run outside of the EDT.

Answer 1

That would have been pretty easy to test (not to say, even typing all the code to test this is less work then posting it here):

import java.awt.EventQueue;
public class HelloWorld {
  public static void main( String[] args ) {
    System.out.println("Hello world");
    System.out.println( EventQueue.isDispatchThread());
  }
}

results in

Hello world
false

on the console.

So yes, System.out.println can be used outside the EDT