net.datastructures
Class NodeQueue<E>

java.lang.Object
  net.datastructures.NodeQueue<E>

All Implemented Interfaces:

Queue<E>

public class NodeQueue<E>
extends Object
implements Queue<E>

Realization of a queue by means of a singly-linked list of nodes. All operations are performed in constant time.

Author:

Roberto Tamassia

Field Summary

protected Node<E>	head
protected int	size
protected Node<E>	tail

Constructor Summary

NodeQueue()
Creates an empty queue.

Method Summary

E	dequeue() Removes the element at the front of the queue.
void	enqueue(E elem) Inserts an element at the rear of the queue.
E	front() Inspects the element at the front of the queue.
boolean	isEmpty() Returns whether the queue is empty.
static void	main(String[] args) Test program that performs a series of operations on on a queue and prints the operation performed, the returned element and the content of the stack after each operation.
int	size() Returns the number of elements in the queue.
static void	status(Queue Q, String op, Object element) Prints information about an operation and the queue.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

head

protected Node<E> head

tail

protected Node<E> tail

size

protected int size

Constructor Detail

NodeQueue

public NodeQueue()

Creates an empty queue.

Method Detail

size

public int size()

Description copied from interface: Queue

Returns the number of elements in the queue.

Specified by:

size in interface Queue<E>

Returns:

number of elements in the queue.

isEmpty

public boolean isEmpty()

Description copied from interface: Queue

Returns whether the queue is empty.

Specified by:

isEmpty in interface Queue<E>

Returns:

true if the queue is empty, false otherwise.

enqueue

public void enqueue(E elem)

Description copied from interface: Queue

Inserts an element at the rear of the queue.

Specified by:

enqueue in interface Queue<E>

Parameters:

elem - new element to be inserted.

front

public E front()
        throws EmptyQueueException

Description copied from interface: Queue

Inspects the element at the front of the queue.

Specified by:

front in interface Queue<E>

Returns:

element at the front of the queue.

Throws:

EmptyQueueException - if the queue is empty.

dequeue

public E dequeue()
          throws EmptyQueueException

Description copied from interface: Queue

Removes the element at the front of the queue.

Specified by:

dequeue in interface Queue<E>

Returns:

element removed.

Throws:

EmptyQueueException - if the queue is empty.

toString

public String toString()

Overrides:

toString in class Object

status

public static void status(Queue Q,
                          String op,
                          Object element)

Prints information about an operation and the queue.

Parameters:

op - operation performed

element - element returned by the operation

main

public static void main(String[] args)

Test program that performs a series of operations on on a queue and prints the operation performed, the returned element and the content of the stack after each operation.