cpsc331.collections

Class ArrayQueue<E>

java.lang.Object

cpsc331.collections.ArrayQueue<E>

All Implemented Interfaces:

BoundedQueue<E>

public class ArrayQueue<E>
extends java.lang.Object
implements BoundedQueue<E>

Provides an implementation of a BoundedQueue using an ArrayList whose capacity is never allowed to change.

The constructor requires time linear in the capacity of the BoundedQueue being created. All other operations require constant time in the worst case.

Constructor Summary

Constructors

Constructor and Description
ArrayQueue(int maxSize) Creates an ArrayQueue whose size and capacity are both equal to the input maxSize, and whose entries are all null, if this is a positive int - throwing an IllegalArgumentException if the input maxSize is negative, instead.

Method Summary

Modifier and Type	Method and Description
int	capacity() Reports the capacity of this bounded queue.
void	insert(E x) Inserts a new entry onto the queue.
boolean	isEmpty() Reports whether the queue is currently empty without changing it.
E	peek() Reports the element at the front of the queue without changing it.
E	remove() Removes an element from the front of the queue and reports it.

Methods inherited from class java.lang.Object

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

Constructor Detail

ArrayQueue

public ArrayQueue(int maxSize)

Creates an ArrayQueue whose size and capacity are both equal to the input maxSize, and whose entries are all null, if this is a positive int - throwing an IllegalArgumentException if the input maxSize is negative, instead.

Parameters:

maxSize - the capacity of the BoundedQueue to be created

Method Detail

insert

public void insert(E x)
            throws QueueFullException

Description copied from interface: BoundedQueue

Inserts a new entry onto the queue.

Specified by:

insert in interface BoundedQueue<E>

Parameters:

x - the object to be inserted onto the queue

Throws:

QueueFullException - if the queue is already full

Precondition:

1. The BoundedQueue Invariant is satisfied.
2. An element x of type E has been given as input.

Postcondition:

1. The BoundedQueue Invariant is satisfied.
2. If the number of objects presently on this bounded queue was less than the bounded queue's capacity, then the input object x has been inserted onto the rear of the queue (which is otherwise unchanged).
3. If the number of objects presently on the bounded queue was equal to the bounded queue's capacity, then a QueueFullException is thrown and the queue is not changed.

peek

public E peek()

Description copied from interface: BoundedQueue

Reports the element at the front of the queue without changing it.

Specified by:

peek in interface BoundedQueue<E>

Returns:

the element at the front of the queue

remove

public E remove()

Description copied from interface: BoundedQueue

Removes an element from the front of the queue and reports it.

Specified by:

remove in interface BoundedQueue<E>

Returns:

the element removed from the queue

isEmpty

public boolean isEmpty()

Description copied from interface: BoundedQueue

Reports whether the queue is currently empty without changing it.

Specified by:

isEmpty in interface BoundedQueue<E>

Returns:

true if the queue is empty, and false otherwise

Precondition:

1. The BoundedQueue Invariant is satisfied.

Postcondition:

1. The BoundedQueue Invariant is satisfied.
2. The bounded queue is not changed.
3. If the bounded queue was empty before this operation then “true” is returned as output.
4. If the bounded queue was not empty before this operation then “false” is returned as output.

capacity

public int capacity()

Description copied from interface: BoundedQueue

Reports the capacity of this bounded queue.

Specified by:

capacity in interface BoundedQueue<E>

Returns:

the capacity of this BoundedQueue

Precondition:

1. The BoundedQueue Invariant is satisfied.

Postcondition:

1. The BoundedQueue Invariant is satisfied.
2. The bounded queue is not changed.
3. The capacity of this bounded queue is returned as output.