public class DoubleArrayFIFOQueue extends java.lang.Object implements DoublePriorityQueue, java.io.Serializable
Instances of this class represent a FIFO queue using a backing
array in a circular way. The array is enlarged and shrunk as needed. You can use the trim()
method
to reduce its memory usage, if necessary.
This class provides additional methods that implement a deque (double-ended queue).
Modifier and Type | Field and Description |
---|---|
static int |
INITIAL_CAPACITY
The standard initial capacity of a queue.
|
Constructor and Description |
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DoubleArrayFIFOQueue()
Creates a new empty queue with standard initial capacity.
|
DoubleArrayFIFOQueue(int capacity)
Creates a new empty queue with given capacity.
|
Modifier and Type | Method and Description |
---|---|
void |
clear()
Removes all elements from this queue.
|
DoubleComparator |
comparator()
Returns the comparator associated with this priority queue, or null if it uses its elements' natural ordering.
|
double |
dequeueDouble()
Dequeues the first element from the queue.
|
double |
dequeueLastDouble()
Dequeues the last element from the queue.
|
void |
enqueue(double x)
Enqueues a new element.
|
void |
enqueueFirst(double x)
Enqueues a new element as the first element (in dequeuing order) of the queue.
|
double |
firstDouble()
Returns the first element of the queue.
|
double |
lastDouble()
Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).
|
int |
size()
Returns the number of elements in this queue.
|
void |
trim()
Trims the queue to the smallest possible size.
|
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
dequeue, enqueue, first, last
changed, isEmpty
public static final int INITIAL_CAPACITY
public DoubleArrayFIFOQueue(int capacity)
capacity
- the initial capacity of this queue.public DoubleArrayFIFOQueue()
public DoubleComparator comparator()
comparator
in interface DoublePriorityQueue
comparator
in interface PriorityQueue<java.lang.Double>
PriorityQueue.comparator()
null
(FIFO queues have no comparator).public double dequeueDouble()
DoublePriorityQueue
dequeueDouble
in interface DoublePriorityQueue
DoublePriorityQueue.dequeue()
public double dequeueLastDouble()
java.util.NoSuchElementException
- if the queue is empty.public void enqueue(double x)
DoublePriorityQueue
enqueue
in interface DoublePriorityQueue
x
- the element to enqueue.PriorityQueue.enqueue(Object)
public void enqueueFirst(double x)
x
- the element to enqueue.public double firstDouble()
DoublePriorityQueue
firstDouble
in interface DoublePriorityQueue
DoublePriorityQueue.first()
public double lastDouble()
DoublePriorityQueue
This default implementation just throws an UnsupportedOperationException
.
lastDouble
in interface DoublePriorityQueue
DoublePriorityQueue.last()
public void clear()
PriorityQueue
clear
in interface PriorityQueue<java.lang.Double>
public void trim()
public int size()
PriorityQueue
size
in interface PriorityQueue<java.lang.Double>