Linked Data Structures - Absolute Java - page 829

TIP: (continued)

It is now easy to defi ne our generic linked list whose clone method produces a deep
copy. The defi nition is given in Display 15.14. We have already discussed the main
points involved in this defi nition. The Programming Example subsection, “A Linked
List with a Deep Copy clone Method ★ ,” discusses some of the minor, but possibly
unclear, details of the defi nition. 1 ■

Display 15.13 The PubliclyCloneable Interface

1 /*
2 The programmer who defines a class implementing this interface
3 has the responsibility to define clone so it makes a deep copy
4 (in the officially sectioned way.)
5 */

6 public interface PubliclyCloneable extends Cloneable
7 {
8 public Object clone( );

9 }

Any class that implements
PubliclyCloneable
automatically implements
Cloneable .

Any class that implements
PubliclyCloneable must have a
public clone method.

Display 15.14 A Generic Linked List with a Deep Copy clone Method (part 1 of 3)

1 public class LinkedList<T extends PubliclyCloneable>
2 implements PubliclyCloneable

3 {
4 private class Node<T>
5 {
6

private T data;

7 private Node<T> link;

8 public Node( )
9 {
10 data = null ;
11 link = null ;
12 }

(continued)

1 You might wonder whether we could use a type parameter in the PubliclyCloneable interface
and so avoid some type casts in the definition copyOf . We could do that, but that may be more trou-
ble than it is worth and, at this introductory level of presentation, would be an unnecessary distraction.