Java Reference
In-Depth Information
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
}
