Linked Data Structures - Absolute Java - page 859

Display 15.29 A Queue Class (part 2 of 2)

25 /**
26 Adds a String to the back of the queue.
27 */
28 public void addToBack(String itemName)
<The definition of this method is defined in Self-Test Exercise 18.>

29 public boolean isEmpty( )
30 {
31

return (front == null );

32 }

33 public void clear( )
34 {
35 front = null ;
36 back = null ;
37 }
38 /**
39 Returns the String in the front of the queue.
40 Returns null if queue is empty.
41 */
42 public String whoIsNext( )
43 {
44

if (front == null )

45 return null ;

46 else

47 return front.item;

48 }
49
50 /**
51 Removes a String from the front of the queue.
52 Returns false if the list is empty.
53 */
54 public boolean removeFront( )
55 {
56 if (front != null )
57 {
58 front = front.link;
59 return true ;

60 }
61 else

62 return false ;

63 }
64 }