horstmann.ch03_queue

Class MessageQueue

java.lang.Object

horstmann.ch03_queue.MessageQueue

public class MessageQueue
extends java.lang.Object

A first-in, first-out bounded collection of messages.

Field Summary

Fields

Modifier and Type	Field and Description
private int	count
private Message[]	elements
private int	head
private int	tail

Constructor Summary

Constructors

Constructor and Description
MessageQueue(int capacity) Constructs an empty message queue.

Method Summary

Modifier and Type	Method and Description
void	add(Message aMessage) Append a message at tail.
boolean	isFull() Checks whether this queue is full
Message	peek() Get message at head.
Message	remove() Remove message at head.
int	size() Get the total number of messages in the queue.

Methods inherited from class java.lang.Object

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

Field Detail

elements

private Message[] elements

head

private int head

tail

private int tail

count

private int count

Constructor Detail

MessageQueue

public MessageQueue(int capacity)

Constructs an empty message queue.

Parameters:

capacity - the maximum capacity of the queue

Precondition: capacity > 0

Method Detail

remove

public Message remove()

Remove message at head.

Returns:

the message that has been removed from the queue

Precondition: size() > 0

add

public void add(Message aMessage)

Append a message at tail.

Parameters:

aMessage - the message to be appended

Precondition: !isFull();

size

public int size()

Get the total number of messages in the queue.

Returns:

the total number of messages in the queue

isFull

public boolean isFull()

Checks whether this queue is full

Returns:

true if the queue is full

peek

public Message peek()

Get message at head.

Returns:

the message that is at the head of the queue

Precondition: size() > 0