一个关于线程的问题？？

Question

System.out.println(DateTimeUtils.formatDate(new Date(),"yyyyMMddHHmmssSSS"));
Thread.sleep(10);
System.out.println(DateTimeUtils.formatDate(new Date(),"yyyyMMddHHmmssSSS"));
Thread.sleep(10);
System.out.println(DateTimeUtils.formatDate(new Date(),"yyyyMMddHHmmssSSS"));
Thread.sleep(10);
System.out.println(DateTimeUtils.formatDate(new Date(),"yyyyMMddHHmmssSSS"));
运行结果：
20090714180903104
20090714180905980
20090714180905996
20090714180905996为什么休眠了10毫秒，而最后两个的毫秒数还是一样呢？？？

Answer 1

10毫秒太短了 jvm不可能这么精确