edu.colorado.collections

Class ObjectQueue

java.lang.Object

edu.colorado.collections.ObjectQueue

All Implemented Interfaces:

java.lang.Cloneable

public class ObjectQueue
extends java.lang.Object
implements java.lang.Cloneable

An ObjectQueue is a queue of references to objects. Limitations: (1) The capacity of one of these queues can change after it's created, but the maximum capacity is limited by the amount of free memory on the machine. The constructor, add, clone, and union will result in an OutOfMemoryError when free memory is exhausted. (2) A queue's capacity cannot exceed the maximum integer 2,147,483,647 (Integer.MAX_VALUE). Any attempt to create a larger capacity results in a failure due to an arithmetic overflow. Java Source Code for this class: http://www.cs.colorado.edu/~main/edu/colorado/collections/ObjectQueue.java

See Also:

ObjectLinkedQueue, BooleanQueue, ByteQueue, CharQueue, DoubleQueue, FloatQueue, IntQueue, LongQueue, ShortQueue

Constructor Summary

Constructors

Constructor and Description
ObjectQueue() Initialize an empty queue with an initial capacity of 10.
ObjectQueue(int initialCapacity) Initialize an empty queue with a specified initial capacity.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	clone() Generate a copy of this queue.
void	ensureCapacity(int minimumCapacity) Change the current capacity of this queue.
int	getCapacity() Accessor method to get the current capacity of this queue.
java.lang.Object	getFront() Get the front item, removing it from this queue.
void	insert(java.lang.Object item) Insert a new item in this queue.
boolean	isEmpty() Determine whether this queue is empty.
int	size() Accessor method to determine the number of items in this queue.
void	trimToSize() Reduce the current capacity of this queue to its actual size (i.e., the number of items it contains).

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectQueue

public ObjectQueue()

Initialize an empty queue with an initial capacity of 10. Note that the insert method works efficiently (without needing more memory) until this capacity is reached. Postcondition: This queue is empty and has an initial capacity of 10.

Throws:

java.lang.OutOfMemoryError - Indicates insufficient memory for: new Object[10].

ObjectQueue

public ObjectQueue(int initialCapacity)

Initialize an empty queue with a specified initial capacity. Note that the insert method works efficiently (without needing more memory) until this capacity is reached.

Parameters:

initialCapacity - the initial capacity of this queue Precondition: initialCapacity is non-negative. Postcondition: This queue is empty and has the given initial capacity.

Throws:

java.lang.IllegalArgumentException - Indicates that initialCapacity is negative.

java.lang.OutOfMemoryError - Indicates insufficient memory for: new Object[initialCapacity].

Method Detail

clone

public java.lang.Object clone()

Generate a copy of this queue.

Overrides:

clone in class java.lang.Object

Returns:

The return value is a copy of this queue. Subsequent changes to the copy will not affect the original, nor vice versa. Note that the return value must be type cast to an ObjectQueue before it can be used.

Throws:

java.lang.OutOfMemoryError - Indicates insufficient memory for creating the clone.

ensureCapacity

public void ensureCapacity(int minimumCapacity)

Change the current capacity of this queue.

Parameters:

minimumCapacity - the new capacity for this queue Postcondition: This queue's capacity has been changed to at least minimumCapacity. If the capacity was already at or greater than minimumCapacity, then the capacity is left unchanged.

Throws:

java.lang.OutOfMemoryError - Indicates insufficient memory for: new Object[minimumCapacity].

getCapacity

public int getCapacity()

Accessor method to get the current capacity of this queue. The insert method works efficiently (without needing more memory) until this capacity is reached.

Returns:

the current capacity of this queue

getFront

public java.lang.Object getFront()

Get the front item, removing it from this queue. Precondition: This queue is not empty.

Returns:

The return value is the front item of this queue, and the item has been removed.

Throws:

java.util.NoSuchElementException - Indicates that this queue is empty.

insert

public void insert(java.lang.Object item)

Insert a new item in this queue. If the addition would take this queue beyond its current capacity, then the capacity is increased before adding the new item. The new item may be the null reference.

Parameters:

item - the item to be pushed onto this queue Postcondition: The item has been pushed onto this queue.

Throws:

java.lang.OutOfMemoryError - Indicates insufficient memory for increasing the queue's capacity. Note: An attempt to increase the capacity beyond Integer.MAX_VALUE will cause the queue to fail with an arithmetic overflow.

isEmpty

public boolean isEmpty()

Determine whether this queue is empty.

Returns:

true if this queue is empty; false otherwise.

size

public int size()

Accessor method to determine the number of items in this queue.

Returns:

the number of items in this queue

trimToSize

public void trimToSize()

Reduce the current capacity of this queue to its actual size (i.e., the number of items it contains). Postcondition: This queue's capacity has been changed to its current size.

Throws:

java.lang.OutOfMemoryError - Indicates insufficient memory for altering the capacity.