@Override
    public int compareTo(PrioritizedTask o) {
        //复写此方法进行任务执行优先级排序
        //      return priority < o.priority ? 1 :
        //          (priority > o.priority ? -1 : 0);
        if(priority < o.priority)
        {
            return -1;
        }else
        {
            if(priority > o.priority)
            {
                return 1;
            }else
            {
                return 0;
            }
        }
    }