Linked Data Structures - Absolute Java - page 856

Display 15.27 A Stack Class (part 2 of 2)

8 public Node( )
9 {
10 item = null ;
11 link = null ;
12 }
13 public Node(String newItem, Node linkValue)
14 {
15 item = newItem;
16 link = linkValue;
17 }
18 } //End of Node inner class

19 private Node head;

20 public Stack( )
21 {
22 head = null ;
23 }

24 /**

25 This method replaces addToStart

26 */
27 public void push(String itemName)
28 {
29 head = new Node(itemName, head);
30 }
31 /**

32 This method replaces deleteHeadNode and

33 also returns the value popped from the list

34 */
35 public String pop( )
36 {
37 if (head == null )

38 throw new IllegalStateException( );

39 else
40 {
41 String returnItem = head.item;
42 head = head.link;
43

return returnItem;

44 }
45 }
46 public boolean isEmpty( )
47 {
48 return (head == null );

49 }
50 }