lab.util

Class Queue<E>

java.lang.Object

lab.util.Queue<E>

Type Parameters:

E - the type of element held in this queue

public class Queue<E>
extends Object

A classic first-in first-out queue data structure.

Constructor Summary

Constructors

Constructor and Description
Queue() Creates an empty queue (size is zero).

Method Summary

Methods

Modifier and Type	Method and Description
E	dequeue() Dequeue an element.
void	enqueue(E element) Enqueue an element.
boolean	equals(Object obj) Compares the specified object to this queue for equality.
int	hashCode() Returns a hash code for this queue.
boolean	isEmpty() Returns true if this queue is empty, and false otherwise.
E	peek() Return the element at the front of the queue without dequeuing the element.
int	size() Returns the number of elements in this queue.
String	toString() Returns a string representation of this queue.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Queue

public Queue()

Creates an empty queue (size is zero).

Method Detail

enqueue

public void enqueue(E element)

Enqueue an element. This operation adds the element to the back of the queue.

Parameters:

element - the element to add to the back of the queue

dequeue

public E dequeue()

Dequeue an element. This operation removes and returns the element at the front of the queue if the queue is not empty.

Throws:

NoSuchElementException - if the queue is empty

Returns:

the element at the front of the queue if the queue is not empty

peek

public E peek()

Return the element at the front of the queue without dequeuing the element.

Throws:

NoSuchElementException - if the queue is empty

Returns:

the element at the front of the queue if the queue is not empty

size

public int size()

Returns the number of elements in this queue.

Returns:

the number of elements in this queue

isEmpty

public boolean isEmpty()

Returns true if this queue is empty, and false otherwise.

Returns:

true if this queue is empty, and false otherwise

hashCode

public int hashCode()

Returns a hash code for this queue. The hash code is computed using the elements of this stack.

Overrides:

hashCode in class Object

See Also:

Object.hashCode()

Returns:

a hash code for this queue

equals

public boolean equals(Object obj)

Compares the specified object to this queue for equality. Two queues are equal if they contain the same number of elements in the same order.

Overrides:

equals in class Object

See Also:

Object.equals(java.lang.Object)

Parameters:

obj - the object to compare to this queue for equality

Returns:

true if the specified object is equal to this queue

toString

public String toString()

Returns a string representation of this queue. The string representation consists of a list of the queue's elements from the front of the queue to the back of the queue, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String.valueOf(Object).

Overrides:

toString in class Object

See Also:

Object.toString()

Returns:

a string representation of this queue