[pron]

It answers the question with a "hello, world." To do more sophisticated stuff, like what you want, you'll need to replace or wrap the standard single-thread Executor with your own Executor. There is exactly one method you need to implement. For example:

    Executor ste = Executors.newSingleThreadExecutor();
    Executor myExecutor = task -> {
      if (task instanceof Thread.VirtualThreadTask vtt) System.out.println("Scheduling " + vtt.thread() + " on " + Thread.currentThread());
      ste.execute(task);
      if (task instanceof Thread.VirtualThreadTask vtt) System.out.println("Descheduled " + vtt.thread() + " from " + Thread.currentThread());
    }
    var myThreadFactory = Thread.builder().virtual(myExecutor).factory();