Java Reference
In-Depth Information
Display 15.25
A Doubly Linked List with an Iterator
(part 1 of 3)
1
import
java.util.NoSuchElementException;
2
public class
DoublyLinkedList
3 {
4
private class
TwoWayNode
5 {
6
private
String item;
7
private
TwoWayNode previous;
8
private
TwoWayNode next;
9
public
TwoWayNode()
10 {
11 item =
null
;
12 next =
null
;
13 previous =
null
;
14 }
15
public
TwoWayNode(String newItem, TwoWayNode previousNode,
TwoWayNode nextNode)
16 {
17 item = newItem;
18 next = nextNode;
19 previous = previousNode;
20 }
21 }
//End of TwoWayNode inner class
22
public class
DoublyLinkedIterator
23 {
24
// We do not need a previous node when using a doubly linked
// list
25
private
TwoWayNode position = null;
26
public
DoublyLinkedIterator( )
27 {
28 position = head;
29 }
30
public void
restart( )
31 {
32 position = head;
33 }
34
public
String next( )
35 {
36
if
(!hasNext( ))
37
throw new
IllegalStateException( );
38 String toReturn = position.item;
39 position = position.next;
40
return
toReturn;
41 }
(continued)
