怎么将Java中的两个Object进行比较

    public boolean add(Object Data)     {        Node a = new Node();        a.data = Data;        if(this.length==0)        {            this.head = a;            this.tail = this.head;            this.head.next = null;        }        else        {            Node p = this.head;            while(p.next!=null)            {                if(p.data<=a.data)                {                    a.next = p.next;                    p.next = a;                }            }        }        return false;    }