Java Reference
In-Depth Information
Display 15.25
A Doubly Linked List with an Iterator
(part 2 of 3)
42
public void
insertHere(String newData)
43 {
44
if
(position ==
null
&& head !=
null
)
45 {
46
// Add to end. First move a temp
47
// pointer to the end of the list
48 TwoWayNode temp = head;
49
while
(temp.next !=
null
)
50 temp = temp.next;
51 temp.next = new TwoWayNode(newData, temp,
null
);
52 }
53
else if
(head ==
null
|| position.previous ==
null
)
54
// at head of list
55 DoublyLinkedList.this.addToStart (newData);
56
else
57 {
58
// Insert before the current position
59 TwoWayNode temp =
new
TwoWayNode(newData,
position. previous, position);
60 position.previous.next = temp;
61 position.previous = temp;
62 }
63 }
64
public void
delete( )
65 {
66
if
(position ==
null
)
67
throw new
IllegalStateException( );
68
else if
(position.previous ==
null
)
69 {
// Deleting first node
70 head = head.next;
71 position = head;
72 }
73
else if
(position.next ==
null
)
74 {
// Deleting last node
75 position.previous.next =
null
;
76 position =
null
;
77 }
78
else
79 {
80 position.previous.next = position.next;
81 position.next.previous = position.previous;
82 position = position.next;
83 }
84 }
85 }
// DoublyLinkedIterator
