Test synchronized block

class Data{ public String name;}
class Sync implements Runnable{
  private Data data;
  Sync(Data dt){data = dt;}
  public void run() {
        synchronized(data){
            data.name = Thread.currentThread().getName();
            print("before: " + data.name);
            try {
                Thread.sleep(1000);
            } catch (InterruptedException x) {
            }
            print("after: " + data.name);
        }
  }

  public static void print(String msg) {
    System.out.println(Thread.currentThread().getName() + ": " + msg);
  }
}

public class TestSynchronized{
  public static void main(String[] args) throws Exception{
    Data id = new Data();
    Sync runA = new Sync(id);
    Sync runB = new Sync(id);
    Thread ta = new Thread(runA, "threadA");
    Thread tb = new Thread(runB, "threadB");
    ta.start();
    tb.start();
 }
}