请代码

请高手指点代码
在Eclipse下编译显示:返回类型与   Object.clone()   不兼容

及类型   Queue   中的方法   enQueue（Object）对于参数（int）不适用
interface   Interface_Queue   {  

//   only   copy   references  
public   Queue   clone();  

//   out   queue   from   head  
//   when   is   empty   ,   return   null  
public   Object   deQueue();  

//   enter   queue   from   tail  
public   void   enQueue(Object   o);  

//   get   the   head   elem   in   the   queue  
//   if   empty   return   null  
public   Object   getHead();  

//   get   the   tail   elem   in   the   queue  
public   Object   getTail();  

public   int   getLength();  

public   boolean   isEmpty();  

//   print   all   the   elem   from   head   to   tail  
//   return   the   print   string  
public   String   printAll();  

//   reverse   all   the   elems   from   head   to   tail  
public   void   reverse();  

public   void   clean();  
}  

public   class   Queue  
implements   Cloneable,   Interface_Queue   {  

class   Node  
implements   Cloneable   {  
Object   elem;  
Node   next;  
Node(Object   elem,   Node   next)   {  
this.elem   =   elem;  
this.next   =   next;  
}  

//   only   copy   references  
public   Node   clone()   {  
try   {  
Node   n   =   (Node)super.clone();  
n.elem   =   this.elem;  
if   (this.next   !=   null)   {  
n.next   =   (Node)this.next.clone();  
}  
else   {  
n.next   =   null;  
}  
return   n;  
}  
catch   (CloneNotSupportedException   ex)   {  
System.err.println( "Ooop:   Clone   Not   Supported   Exception ");  
ex.printStackTrace();  
}  
return   null;  
}  
}  

//   have   head   node  
//   when   the   queue   is   empty,the   head   and   tail   point   to   the   same   head   node  
//   enQueue   from   tail  
//   deQueue   from   head  
private   Node   head   =   new   Node(null,   null);  
private   Node   tail   =   head;  
private   int   length   =   0;  

//   only   copy   references  
public   Queue   clone()   {  
try   {  
Queue   n   =   (Queue)super.clone();  
n.head   =   this.head.clone();  
Node   p   =   n.head;  
while   (p.next   !=   null)   {  
p   =   p.next;  
}  
n.tail   =   p;