Linked Data Structures - Absolute Java - page 858

The definition of a simple Queue class that is based on a linked list is given in
Display 15.29. A short demonstration program is given in Display 15.30. We have not
made our queue a generic queue to keep the definition simple, but it would be routine
to replace the data type String with a type parameter.

Queue
A queue is a first-in/first-out data structure; that is, the data items are removed from the
queue in the same order that they were added to the queue.

Display 15.29 A Queue Class (part 1 of 2)

1 public class Queue
2 {
3 private class Node
4 {
5 private String item;

6 private Node link;

7 public Node( )
8 {
9 item = null ;
10 link = null ;
11 }

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

18 private Node front;

19 private Node back;

20 public Queue( )
21 {
22 front = null ;
23 back = null ;
24 }