Problem figuring out threading problem for SCJP

Hi

I have the following code

-------------------------------------- <snip>
class MyThread extends Thread {
           String sa;
           public MyThread(String sa) {
                 this.sa = sa;
           }

           public void run() {
               synchronized(sa) {
                    while(!sa.equals("Done)) {
                       try { sa.wait(); } catch (InterruptedException
e) {}
                    }
               }
               System.out.println(sa);
           }
}

class Test {
           private static String sa = new String("Not Done");
           public static void main(String [] args) {
                 MyThread t1 = new MyThread(sa);
                 t1.start();
                 synchronized(sa) {
                     sa = new String("Done");
                     sa.notify();
                 }
            }
}

</snip>------------------------------------------------

I am not sure how to interpret this. I'm trying to find out what
thread has the lock on the object sa (in the Test object). I'm not
sure if it matters if its a String (immutable) object and that it is a
static object being synchronised.

If it is being synchronised in a different thread (main and t1), does
it matter?

Cheers
Patrick