关于synchronized有趣的同步问题

public class SyncThreadTest extends Thread {
  public static Integer count = 0;
  private static final int TIMES = 10000;
  public SyncThreadTest(){
    super("SyncThread");
  }
  @Override
  public void run(){
    synchronized (count){
      for (int i = 0; i < TIMES; i ++){
        count++;
      }
    }
  }
  public static void main(String[] args) throws InterruptedException{
    SyncThreadTest t1 = new SyncThreadTest();
    SyncThreadTest t2 = new SyncThreadTest();
    t1.start();
    t2.start();
    t1.join();
    t2.join();
    System.out.println(count);
  }
}